US20120255731A1 - Process for producing mineral oil from underground formations - Google Patents
Process for producing mineral oil from underground formations Download PDFInfo
- Publication number
- US20120255731A1 US20120255731A1 US13/440,049 US201213440049A US2012255731A1 US 20120255731 A1 US20120255731 A1 US 20120255731A1 US 201213440049 A US201213440049 A US 201213440049A US 2012255731 A1 US2012255731 A1 US 2012255731A1
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- 238000000034 method Methods 0.000 title claims abstract description 101
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 96
- 239000002480 mineral oil Substances 0.000 title claims abstract description 59
- 235000010446 mineral oil Nutrition 0.000 title claims abstract description 57
- 230000008569 process Effects 0.000 title claims abstract description 46
- 238000005755 formation reaction Methods 0.000 title abstract description 91
- 229920001577 copolymer Polymers 0.000 claims abstract description 135
- 239000013011 aqueous formulation Substances 0.000 claims abstract description 38
- 239000000178 monomer Substances 0.000 claims description 229
- 229920000642 polymer Polymers 0.000 claims description 103
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 95
- 229910001868 water Inorganic materials 0.000 claims description 93
- -1 hydrocarbyl radical Chemical class 0.000 claims description 76
- 239000000203 mixture Substances 0.000 claims description 75
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 54
- 238000002347 injection Methods 0.000 claims description 48
- 239000007924 injection Substances 0.000 claims description 48
- 238000004519 manufacturing process Methods 0.000 claims description 45
- 238000009472 formulation Methods 0.000 claims description 38
- 125000004432 carbon atom Chemical group C* 0.000 claims description 33
- 150000003254 radicals Chemical class 0.000 claims description 29
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 27
- 150000003839 salts Chemical class 0.000 claims description 25
- 125000000129 anionic group Chemical group 0.000 claims description 16
- 230000000903 blocking effect Effects 0.000 claims description 16
- 125000002091 cationic group Chemical group 0.000 claims description 14
- 150000001875 compounds Chemical class 0.000 claims description 13
- 238000004132 cross linking Methods 0.000 claims description 12
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 9
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 8
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 8
- 125000001931 aliphatic group Chemical group 0.000 claims description 7
- 125000001033 ether group Chemical group 0.000 claims description 7
- 229910006069 SO3H Inorganic materials 0.000 claims description 6
- 230000002378 acidificating effect Effects 0.000 claims description 6
- 125000003118 aryl group Chemical group 0.000 claims description 6
- 125000005647 linker group Chemical group 0.000 claims description 6
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 claims description 6
- 150000003926 acrylamides Chemical class 0.000 claims description 5
- 150000001252 acrylic acid derivatives Chemical class 0.000 claims description 5
- 229920006317 cationic polymer Polymers 0.000 claims description 4
- 229910018828 PO3H2 Inorganic materials 0.000 claims description 3
- OCBFFGCSTGGPSQ-UHFFFAOYSA-N [CH2]CC Chemical group [CH2]CC OCBFFGCSTGGPSQ-UHFFFAOYSA-N 0.000 claims description 3
- 150000001299 aldehydes Chemical class 0.000 claims description 3
- 125000000217 alkyl group Chemical group 0.000 claims description 3
- 229910021645 metal ion Inorganic materials 0.000 claims description 3
- 150000002894 organic compounds Chemical class 0.000 claims description 3
- 125000003277 amino group Chemical group 0.000 claims 1
- 239000000499 gel Substances 0.000 description 70
- 239000004971 Cross linker Substances 0.000 description 48
- 238000006116 polymerization reaction Methods 0.000 description 45
- 238000002360 preparation method Methods 0.000 description 44
- 239000000243 solution Substances 0.000 description 43
- 239000013535 sea water Substances 0.000 description 21
- 239000003921 oil Substances 0.000 description 19
- 239000013505 freshwater Substances 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 16
- PQUXFUBNSYCQAL-UHFFFAOYSA-N 1-(2,3-difluorophenyl)ethanone Chemical compound CC(=O)C1=CC=CC(F)=C1F PQUXFUBNSYCQAL-UHFFFAOYSA-N 0.000 description 13
- 125000002947 alkylene group Chemical group 0.000 description 13
- 229940047670 sodium acrylate Drugs 0.000 description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 12
- 239000003054 catalyst Substances 0.000 description 12
- 239000003999 initiator Substances 0.000 description 12
- 150000001298 alcohols Chemical class 0.000 description 11
- 239000007864 aqueous solution Substances 0.000 description 11
- 239000004094 surface-active agent Substances 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 229920000536 2-Acrylamido-2-methylpropane sulfonic acid Polymers 0.000 description 10
- XHZPRMZZQOIPDS-UHFFFAOYSA-N 2-Methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonic acid Chemical compound OS(=O)(=O)CC(C)(C)NC(=O)C=C XHZPRMZZQOIPDS-UHFFFAOYSA-N 0.000 description 10
- 239000002609 medium Substances 0.000 description 10
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical group C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 9
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 7
- 229940048053 acrylate Drugs 0.000 description 7
- 230000035699 permeability Effects 0.000 description 7
- 235000013877 carbamide Nutrition 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 230000002209 hydrophobic effect Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 6
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 6
- 239000011435 rock Substances 0.000 description 6
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 6
- 230000008719 thickening Effects 0.000 description 6
- 230000007704 transition Effects 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 5
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 5
- 239000004202 carbamide Substances 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 239000007858 starting material Substances 0.000 description 5
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 4
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 4
- 229920002873 Polyethylenimine Polymers 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 4
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 125000004185 ester group Chemical group 0.000 description 4
- 239000008187 granular material Substances 0.000 description 4
- 125000001183 hydrocarbyl group Chemical group 0.000 description 4
- 125000001165 hydrophobic group Chemical group 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 4
- 125000000740 n-pentyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 4
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 4
- 239000002736 nonionic surfactant Substances 0.000 description 4
- 229920002401 polyacrylamide Polymers 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 125000001424 substituent group Chemical group 0.000 description 4
- ISXSCDLOGDJUNJ-UHFFFAOYSA-N tert-butyl prop-2-enoate Chemical compound CC(C)(C)OC(=O)C=C ISXSCDLOGDJUNJ-UHFFFAOYSA-N 0.000 description 4
- CIHOLLKRGTVIJN-UHFFFAOYSA-N tert‐butyl hydroperoxide Chemical compound CC(C)(C)OO CIHOLLKRGTVIJN-UHFFFAOYSA-N 0.000 description 4
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 3
- SYURNNNQIFDVCA-UHFFFAOYSA-N 2-propyloxirane Chemical group CCCC1CO1 SYURNNNQIFDVCA-UHFFFAOYSA-N 0.000 description 3
- 239000004435 Oxo alcohol Substances 0.000 description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 3
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical group C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 3
- LXEKPEMOWBOYRF-UHFFFAOYSA-N [2-[(1-azaniumyl-1-imino-2-methylpropan-2-yl)diazenyl]-2-methylpropanimidoyl]azanium;dichloride Chemical compound Cl.Cl.NC(=N)C(C)(C)N=NC(C)(C)C(N)=N LXEKPEMOWBOYRF-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 125000005529 alkyleneoxy group Chemical group 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 3
- 150000001450 anions Chemical class 0.000 description 3
- 239000012736 aqueous medium Substances 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 150000002148 esters Chemical class 0.000 description 3
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 3
- 239000000693 micelle Substances 0.000 description 3
- 125000001280 n-hexyl group Chemical group C(CCCCC)* 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- LQPLDXQVILYOOL-UHFFFAOYSA-I pentasodium;2-[bis[2-[bis(carboxylatomethyl)amino]ethyl]amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC(=O)[O-])CCN(CC([O-])=O)CC([O-])=O LQPLDXQVILYOOL-UHFFFAOYSA-I 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 229920000233 poly(alkylene oxides) Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000012966 redox initiator Substances 0.000 description 3
- 238000012552 review Methods 0.000 description 3
- 235000010265 sodium sulphite Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 238000012719 thermal polymerization Methods 0.000 description 3
- ZTWTYVWXUKTLCP-UHFFFAOYSA-N vinylphosphonic acid Chemical compound OP(O)(=O)C=C ZTWTYVWXUKTLCP-UHFFFAOYSA-N 0.000 description 3
- WULAHPYSGCVQHM-UHFFFAOYSA-N 2-(2-ethenoxyethoxy)ethanol Chemical compound OCCOCCOC=C WULAHPYSGCVQHM-UHFFFAOYSA-N 0.000 description 2
- HMBNQNDUEFFFNZ-UHFFFAOYSA-N 4-ethenoxybutan-1-ol Chemical compound OCCCCOC=C HMBNQNDUEFFFNZ-UHFFFAOYSA-N 0.000 description 2
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 description 2
- GAWIXWVDTYZWAW-UHFFFAOYSA-N C[CH]O Chemical group C[CH]O GAWIXWVDTYZWAW-UHFFFAOYSA-N 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 2
- WQDUMFSSJAZKTM-UHFFFAOYSA-N Sodium methoxide Chemical compound [Na+].[O-]C WQDUMFSSJAZKTM-UHFFFAOYSA-N 0.000 description 2
- 238000010795 Steam Flooding Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N alpha-ketodiacetal Natural products O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 description 2
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 239000003125 aqueous solvent Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229920001400 block copolymer Polymers 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 150000007942 carboxylates Chemical group 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 description 2
- 239000013530 defoamer Substances 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000006266 etherification reaction Methods 0.000 description 2
- 239000008398 formation water Substances 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical class C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 125000002768 hydroxyalkyl group Chemical group 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 229910001629 magnesium chloride Inorganic materials 0.000 description 2
- ZQXSMRAEXCEDJD-UHFFFAOYSA-N n-ethenylformamide Chemical compound C=CNC=O ZQXSMRAEXCEDJD-UHFFFAOYSA-N 0.000 description 2
- 125000003136 n-heptyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920006254 polymer film Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- UIIIBRHUICCMAI-UHFFFAOYSA-N prop-2-ene-1-sulfonic acid Chemical compound OS(=O)(=O)CC=C UIIIBRHUICCMAI-UHFFFAOYSA-N 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 125000002914 sec-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 229910001379 sodium hypophosphite Inorganic materials 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 229920001567 vinyl ester resin Polymers 0.000 description 2
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 2
- NLVXSWCKKBEXTG-UHFFFAOYSA-N vinylsulfonic acid Chemical compound OS(=O)(=O)C=C NLVXSWCKKBEXTG-UHFFFAOYSA-N 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- 125000004178 (C1-C4) alkyl group Chemical group 0.000 description 1
- 125000004169 (C1-C6) alkyl group Chemical group 0.000 description 1
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 1
- CRSBERNSMYQZNG-UHFFFAOYSA-N 1 -dodecene Natural products CCCCCCCCCCC=C CRSBERNSMYQZNG-UHFFFAOYSA-N 0.000 description 1
- RBACIKXCRWGCBB-UHFFFAOYSA-N 1,2-Epoxybutane Chemical group CCC1CO1 RBACIKXCRWGCBB-UHFFFAOYSA-N 0.000 description 1
- JWYVGKFDLWWQJX-UHFFFAOYSA-N 1-ethenylazepan-2-one Chemical compound C=CN1CCCCCC1=O JWYVGKFDLWWQJX-UHFFFAOYSA-N 0.000 description 1
- AKEGTQKKWUFLBQ-UHFFFAOYSA-N 2,4,4-trimethyl-2-(prop-2-enoylamino)pentane-1-sulfonic acid Chemical compound CC(C)(C)CC(C)(CS(O)(=O)=O)NC(=O)C=C AKEGTQKKWUFLBQ-UHFFFAOYSA-N 0.000 description 1
- FTLNISJYMDEXNR-UHFFFAOYSA-N 2-(2-ethenoxypropoxy)propan-1-ol Chemical compound OCC(C)OCC(C)OC=C FTLNISJYMDEXNR-UHFFFAOYSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- YQSVYZPYIXAYND-UHFFFAOYSA-N 2-(prop-2-enoylamino)butane-1-sulfonic acid Chemical compound OS(=O)(=O)CC(CC)NC(=O)C=C YQSVYZPYIXAYND-UHFFFAOYSA-N 0.000 description 1
- PVJHTWVUDWZKFY-UHFFFAOYSA-N 2-butoxyethenol Chemical compound CCCCOC=CO PVJHTWVUDWZKFY-UHFFFAOYSA-N 0.000 description 1
- WVVKLQLZCOWLJE-UHFFFAOYSA-N 2-ethoxyethenol Chemical compound CCOC=CO WVVKLQLZCOWLJE-UHFFFAOYSA-N 0.000 description 1
- LYPJRFIBDHNQLY-UHFFFAOYSA-J 2-hydroxypropanoate;zirconium(4+) Chemical compound [Zr+4].CC(O)C([O-])=O.CC(O)C([O-])=O.CC(O)C([O-])=O.CC(O)C([O-])=O LYPJRFIBDHNQLY-UHFFFAOYSA-J 0.000 description 1
- VSSGDAWBDKMCMI-UHFFFAOYSA-N 2-methyl-2-(2-methylprop-2-enoylamino)propane-1-sulfonic acid Chemical compound CC(=C)C(=O)NC(C)(C)CS(O)(=O)=O VSSGDAWBDKMCMI-UHFFFAOYSA-N 0.000 description 1
- SSONCJTVDRSLNK-UHFFFAOYSA-N 2-methylprop-2-enoic acid;hydrochloride Chemical compound Cl.CC(=C)C(O)=O SSONCJTVDRSLNK-UHFFFAOYSA-N 0.000 description 1
- RFYRKVOQWIYXRI-UHFFFAOYSA-N 2-propoxyethenol Chemical compound CCCOC=CO RFYRKVOQWIYXRI-UHFFFAOYSA-N 0.000 description 1
- NECRQCBKTGZNMH-UHFFFAOYSA-N 3,5-dimethylhex-1-yn-3-ol Chemical compound CC(C)CC(C)(O)C#C NECRQCBKTGZNMH-UHFFFAOYSA-N 0.000 description 1
- IDEYMPQPNBAJHG-UHFFFAOYSA-N 3-methyl-3-(prop-2-enoylamino)butane-1-sulfonic acid Chemical compound OS(=O)(=O)CCC(C)(C)NC(=O)C=C IDEYMPQPNBAJHG-UHFFFAOYSA-N 0.000 description 1
- XWNSFEAWWGGSKJ-UHFFFAOYSA-N 4-acetyl-4-methylheptanedinitrile Chemical compound N#CCCC(C)(C(=O)C)CCC#N XWNSFEAWWGGSKJ-UHFFFAOYSA-N 0.000 description 1
- YYWNXJKMAJYRSP-UHFFFAOYSA-N 4-carbamoylpent-4-enyl(trimethyl)azanium;chloride Chemical compound [Cl-].C[N+](C)(C)CCCC(=C)C(N)=O YYWNXJKMAJYRSP-UHFFFAOYSA-N 0.000 description 1
- ZUGAOYSWHHGDJY-UHFFFAOYSA-K 5-hydroxy-2,8,9-trioxa-1-aluminabicyclo[3.3.2]decane-3,7,10-trione Chemical compound [Al+3].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O ZUGAOYSWHHGDJY-UHFFFAOYSA-K 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- 101100352919 Caenorhabditis elegans ppm-2 gene Proteins 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- RUPBZQFQVRMKDG-UHFFFAOYSA-M Didecyldimethylammonium chloride Chemical compound [Cl-].CCCCCCCCCC[N+](C)(C)CCCCCCCCCC RUPBZQFQVRMKDG-UHFFFAOYSA-M 0.000 description 1
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 1
- IMROMDMJAWUWLK-UHFFFAOYSA-N Ethenol Chemical group OC=C IMROMDMJAWUWLK-UHFFFAOYSA-N 0.000 description 1
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000002841 Lewis acid Substances 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004153 Potassium bromate Substances 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 241000364021 Tulsa Species 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- QYKIQEUNHZKYBP-UHFFFAOYSA-N Vinyl ether Chemical class C=COC=C QYKIQEUNHZKYBP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 229910007564 Zn—Co Inorganic materials 0.000 description 1
- 0 [4*]C1CO1.[4*]OCC1CO1 Chemical compound [4*]C1CO1.[4*]OCC1CO1 0.000 description 1
- WDNIVTZNAPEMHF-UHFFFAOYSA-N acetic acid;chromium Chemical compound [Cr].CC(O)=O.CC(O)=O WDNIVTZNAPEMHF-UHFFFAOYSA-N 0.000 description 1
- 238000007171 acid catalysis Methods 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 125000003545 alkoxy group Chemical group 0.000 description 1
- 150000008051 alkyl sulfates Chemical class 0.000 description 1
- 239000002168 alkylating agent Substances 0.000 description 1
- 229940100198 alkylating agent Drugs 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 239000012431 aqueous reaction media Substances 0.000 description 1
- 239000003139 biocide Substances 0.000 description 1
- 229920001222 biopolymer Polymers 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 235000011148 calcium chloride Nutrition 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001723 carbon free-radicals Chemical class 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- BFGKITSFLPAWGI-UHFFFAOYSA-N chromium(3+) Chemical compound [Cr+3] BFGKITSFLPAWGI-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229920006037 cross link polymer Polymers 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- DENRZWYUOJLTMF-UHFFFAOYSA-N diethyl sulfate Chemical compound CCOS(=O)(=O)OCC DENRZWYUOJLTMF-UHFFFAOYSA-N 0.000 description 1
- 229940008406 diethyl sulfate Drugs 0.000 description 1
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical class C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 description 1
- VAYGXNSJCAHWJZ-UHFFFAOYSA-N dimethyl sulfate Chemical compound COS(=O)(=O)OC VAYGXNSJCAHWJZ-UHFFFAOYSA-N 0.000 description 1
- YIOJGTBNHQAVBO-UHFFFAOYSA-N dimethyl-bis(prop-2-enyl)azanium Chemical class C=CC[N+](C)(C)CC=C YIOJGTBNHQAVBO-UHFFFAOYSA-N 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 229940069096 dodecene Drugs 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- UYMKPFRHYYNDTL-UHFFFAOYSA-N ethenamine Chemical group NC=C UYMKPFRHYYNDTL-UHFFFAOYSA-N 0.000 description 1
- GFJVXXWOPWLRNU-UHFFFAOYSA-N ethenyl formate Chemical compound C=COC=O GFJVXXWOPWLRNU-UHFFFAOYSA-N 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 229940015043 glyoxal Drugs 0.000 description 1
- 239000004312 hexamethylene tetramine Chemical class 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010952 in-situ formation Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- CPJRRXSHAYUTGL-UHFFFAOYSA-N isopentenyl alcohol Chemical compound CC(=C)CCO CPJRRXSHAYUTGL-UHFFFAOYSA-N 0.000 description 1
- 150000007517 lewis acids Chemical class 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 235000013372 meat Nutrition 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 125000001570 methylene group Chemical group [H]C([H])([*:1])[*:2] 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- AWDYCSUWSUENQK-UHFFFAOYSA-N n-decylprop-2-enamide Chemical compound CCCCCCCCCCNC(=O)C=C AWDYCSUWSUENQK-UHFFFAOYSA-N 0.000 description 1
- RQAKESSLMFZVMC-UHFFFAOYSA-N n-ethenylacetamide Chemical compound CC(=O)NC=C RQAKESSLMFZVMC-UHFFFAOYSA-N 0.000 description 1
- 210000003739 neck Anatomy 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical compound CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 description 1
- 239000012053 oil suspension Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000002572 peristaltic effect Effects 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 239000003505 polymerization initiator Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229940094037 potassium bromate Drugs 0.000 description 1
- 235000019396 potassium bromate Nutrition 0.000 description 1
- BDAWXSQJJCIFIK-UHFFFAOYSA-N potassium methoxide Chemical compound [K+].[O-]C BDAWXSQJJCIFIK-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- RZKYDQNMAUSEDZ-UHFFFAOYSA-N prop-2-enylphosphonic acid Chemical compound OP(O)(=O)CC=C RZKYDQNMAUSEDZ-UHFFFAOYSA-N 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000010526 radical polymerization reaction Methods 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 150000008028 secondary esters Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229940083575 sodium dodecyl sulfate Drugs 0.000 description 1
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- FWFUWXVFYKCSQA-UHFFFAOYSA-M sodium;2-methyl-2-(prop-2-enoylamino)propane-1-sulfonate Chemical compound [Na+].[O-]S(=O)(=O)CC(C)(C)NC(=O)C=C FWFUWXVFYKCSQA-UHFFFAOYSA-M 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 125000005504 styryl group Chemical group 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 150000008027 tertiary esters Chemical group 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 150000003672 ureas Chemical class 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
- GBNDTYKAOXLLID-UHFFFAOYSA-N zirconium(4+) ion Chemical class [Zr+4] GBNDTYKAOXLLID-UHFFFAOYSA-N 0.000 description 1
- MFFVROSEPLMJAP-UHFFFAOYSA-J zirconium(4+);tetraacetate Chemical compound [Zr+4].CC([O-])=O.CC([O-])=O.CC([O-])=O.CC([O-])=O MFFVROSEPLMJAP-UHFFFAOYSA-J 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/56—Compositions for consolidating loose sand or the like around wells without excessively decreasing the permeability thereof
- C09K8/57—Compositions based on water or polar solvents
- C09K8/575—Compositions based on water or polar solvents containing organic compounds
- C09K8/5751—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/512—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/56—Compositions for consolidating loose sand or the like around wells without excessively decreasing the permeability thereof
- C09K8/57—Compositions based on water or polar solvents
- C09K8/575—Compositions based on water or polar solvents containing organic compounds
- C09K8/5751—Macromolecular compounds
- C09K8/5756—Macromolecular compounds containing cross-linking agents
Definitions
- the present invention relates to a process for producing mineral oil from underground formations, wherein, in one process step, permeable regions of the underground formation are blocked by injecting aqueous formulations of hydrophobically associating copolymers into the formation.
- mineral oil occurs in the cavities of porous reservoir rocks which are closed off from the surface of the earth by impervious covering layers.
- the cavities may be very fine cavities, capillaries, pores or the like. Fine pore necks may, for example, have a diameter of only approx. 1 ⁇ m.
- the underground formation may additionally also have regions with pores of greater diameter and/or natural fractures.
- a deposit In addition to mineral oil, including proportions of natural gas, a deposit generally comprises water with a greater or lesser salt content.
- mineral oil After a well has been sunk into the oil-bearing strata, mineral oil at first flows to the production wells owing to the natural deposit pressure, and is flushed to the surface of the earth.
- This phase of mineral oil production is known by the person skilled in the art as primary production.
- flush production generally ceases very rapidly, especially under poor deposit conditions, for example a high oil viscosity, rapidly declining deposit pressure or high flow resistances in the oil-bearing strata.
- With primary production it is possible to produce an average of only 2 to 10% of the oil originally present in the deposit. In the case of higher-viscosity mineral oils, flush production is generally completely impossible.
- water flooding One secondary mineral oil production process is called “water flooding”.
- the deposit is provided with one or more injection wells in addition to the production wells, i.e. the wells through which mineral oil is withdrawn from the mineral oil formation.
- Water is injected into the oil-bearing strata through the injection wells. This artificially increases the deposit pressure and forces the oil from the injection wells in the direction of the production wells.
- Water flooding can significantly enhance the exploitation level.
- steam flooding steam into the deposit (“steam flooding”). This is advisable especially when the deposit comprises high-viscosity oils.
- a water front proceeding from the injection well should force the oil homogeneously over the entire mineral oil formation to the production well.
- a mineral oil formation has regions with different levels of flow resistance.
- regions with a low flow resistance to water for example natural or synthetic fractures or very permeable regions in the reservoir rock. The permeable regions may also be already exploited regions.
- the flooding water injected naturally flows principally through flow paths with low flow resistance from the injection well to the production well, while there is at least slower flow, if any, of water through the fine-porosity, oil-saturated deposit regions with high flow resistance.
- the water thus no longer flows homogeneously through the formation, and the water front is instead very irregular (called “fingering”), and an increasing amount of water and a decreasing amount of mineral oil are produced via the production well.
- fingering very irregular
- the person skilled in the art refers to “watering out of production”.
- the effects mentioned are particularly marked in the case of heavy and viscous mineral oils. The higher the mineral oil viscosity, the more probable is rapid watering out of production. The problem occurs especially in the presence of fissured rock formations (called “fractured reservoirs”).
- formulations for blocking of highly permeable regions of underground formations, i.e. for conformance control, it is possible to use comparatively low-viscosity formulations of particular chemical substances which can be injected readily into the formation, and the viscosity of which rises significantly only after injection into the formation, under the conditions which exist in the formation.
- Such formulations comprise inorganic, organic or polymeric components suitable for increasing viscosity.
- the rise in viscosity of the injected formulation can occur, for example, with a simple time delay, and/or the rise in viscosity can be triggered by the temperature rise when the injected formulation in the deposit gradually heats up to the deposit temperature.
- Formulations whose viscosity rises only under formation conditions are known, for example, as “thermogels” or “delayed gelling systems”.
- SU 1 654 554 A1 discloses a process for producing oil using mixtures of aluminum chloride or aluminum nitrate, urea and water, which are injected into the mineral oil formation.
- the formulations naturally flow preferably along the flow paths with the lowest flow resistance.
- the urea is hydrolyzed to carbon dioxide and ammonia.
- the release of the ammonia base significantly increases the pH of the water, and a high-viscosity gel of aluminum hydroxide precipitates out, which blocks the highly permeable zones.
- US 2008/0035344 A1 discloses a mixture for blocking of underground formations with retarded gelation, which comprises at least one acid-soluble, crosslinkable polymer, for example partly hydrolyzed polyacrylamide, a partly neutralized aluminum salt, for example an aluminum hydroxide chloride, and an activator which can release bases under formation conditions, for example urea, substituted ureas or hexamethylenetetramine.
- the mixture can preferably be used at a temperature of 0 to 40° C. and gelates at temperatures above 50° C., according to the use conditions, within 2 h to 10 days.
- RU 2 361 074 discloses a process for blocking highly permeable zones, in which portions of formulations based on urea and aluminum salts are injected into a deposit with high deposit temperature.
- U.S. Pat. No. 4,182,417, US 2007/0204989, WO 2007/126318 A1 and WO 2010/069607 A1 disclose water-swellable particles for blocking of underground formations. These particles can be injected in a suitable formulation into the underground formation, swell in the formation under the influence of the formation water and in this manner block highly permeable regions of the formation.
- U.S. Pat. No. 4,613,631 discloses gels formed from crosslinked polymers for blocking of underground formations.
- the polymers may, for example, be polyacrylamide, polyacrylic acids, or else biopolymers, for example xanthogenates.
- the crosslinkers used are organic compounds which have at least two positively charged nitrogen atoms.
- U.S. Pat. No. 7,150,319 B2 discloses a process for blocking underground formations, in which a copolymer comprising 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, a further nitrogen-containing monomer, for example N-vinylformamide or N-vinylpyrrolidone, and vinylphosphonic acid as monomers.
- the copolymer is crosslinked with compounds of chromium, zirconium, titanium or aluminum to form a viscous gel.
- U.S. Pat. No. 6,803,348 B2 discloses a process for reducing water production from mineral oil-bearing underground formations, in which water-soluble, hydrophobically associating copolymers comprising a linear hydrophilic main chain, hydrophobic side groups and functional groups which can be used for crosslinking are used.
- the water-soluble copolymers are injected into the underground formation and crosslinked therein, for example by means of Cr(III) ions, Zr(IV) ions or aldehydes.
- the polymers are preferably based on polyacrylamides.
- the hydrophobic groups are preferably alkyl groups having at least 6, preferably at least 8 and more preferably at least 12 carbon atoms.
- the copolymer may comprise, for example, N-alkylacrylamides, for example N-decylacrylamide, as a monomer.
- WO 2010/133527 A2 discloses hydrophobically associating copolymers which comprise at least hydrophilic, monoethylenically unsaturated monomers, for example acrylamide, and monoethylenically unsaturated, hydrophobically associating monomers.
- the hydrophobically associating monomers have a block structure and have—in this sequence—an ethylenically unsaturated group, optionally a linking group, a first polyoxyalkylene block which comprises at least 50 mol % of ethyleneoxy groups, and a second polyoxyalkylene block which consists of alkyleneoxy groups having at least 4 carbon atoms.
- the application discloses the use of such copolymers as thickeners, for example for polymer flooding, for construction chemical applications, or for detergent formulations.
- WO 2011/015520 A1 discloses a process for preparing hydrophobically associating copolymers by polymerizing water-soluble, monoethylenically unsaturated, surface-active monomers and monoethylenically unsaturated hydrophilic monomers in the presence of surfactants, and the use of such copolymers for polymer flooding.
- EP 10192323.3, EP 10192334.0 and EP 10192316.7 disclose the use of the hydrophobically associating copolymers disclosed in WO 2010/133527 A2 in specific processes for polymer flooding.
- FIG. 1 illustrates the results of the viscosity measurements.
- the process according to the invention comprises at least two process steps, (1) and (2).
- permeable regions of the underground mineral oil deposit are blocked by injecting an aqueous formulation through at least one well sunk into the formation, said aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer.
- blocking means here that the permeable regions are completely or at least partially blocked. “Partially blocked” is intended to mean that the flow resistance of the permeable regions for aqueous media increases due to the treatment with the aqueous formulation of the copolymer.
- process step (2) mineral oil is actually produced by injecting an aqueous flooding medium into at least one injection well and withdrawing mineral oil through at least one production well.
- the injected aqueous flooding medium maintains the pressure and forces the mineral oil from the injection wells in the direction of the production wells.
- process step (1) i.e. the blocking of permeable zones
- the flooding medium injected in process step (2) is forced also to flow through less permeable, as yet unexploited regions of the underground formation.
- the mineral oil yield is increased and water production is reduced.
- Process steps (1) and (2) can also be performed more than once in the context of the process according to the invention, and the process according to the invention may of course comprise further process steps.
- the mineral oil deposits to which the process according to the invention is applied may be deposits for all kinds of oil, for example those for light or heavy oil.
- the deposits generally comprise deposit water with a greater or lesser salt content.
- Typical salts in deposit waters comprise especially alkali metal salts and alkaline earth metal salts.
- Examples of typical cations comprise Na + , K + , Mg 2+ and Ca 2+
- examples of typical anions comprise chloride, bromide, hydrogencarbonate, sulfate or borate.
- the process according to the invention is especially suitable for deposits with a total amount of all salts in the deposit water of 20 000 ppm to 350 000 ppm (parts by weight), preferably 100 000 ppm to 250 000 ppm.
- the amount of alkaline earth metal ions in the deposit water may especially be 1000 to 53 000 ppm.
- the mineral oil deposits have inhomogeneous permeability. This is understood to mean that the permeability is not the same in all regions of the deposit, and that the deposit instead has regions of higher and lower permeability. Regions of higher permeability may be caused, for example, by the fact that the deposits have larger pores in this region, or else by the fact that the deposits have fractures, cracks, fissures or the like.
- water flooding the water injected, due to the low flow resistance, flows preferentially through the regions of high permeability.
- the deposit may also have different rock layers of different permeability arranged one on top of another.
- a deposit may comprise a comparatively permeable layer essentially comprising water, and a lower, less permeable layer comprising mineral oil.
- the deposit temperatures (T L ) are in the range from 20° C. to 120° C., especially 30° C. to 120° C., preferably 35° C. to 110° C., more preferably 40° C. to 100° C., even more preferably 45° C. to 90° C. and, for example, 50° C. to 75° C. It will be clear to the person skilled in the art that a mineral oil deposit may also have a certain temperature distribution.
- the deposit temperature mentioned relates to the region of the deposit between the injection and production wells, i.e. the region covered by process steps (1) and (2).
- the temperature distribution can generally be undertaken from temperature measurements at particular sites in the formation in combination with simulation calculations, the simulation calculations taking account of factors including amounts of heat introduced into the formation and the amounts of heat removed from the formation.
- At least one well is sunk into the mineral oil deposit, through which the aqueous copolymer formulation can be injected to block permeable regions.
- This may be a well which has been sunk specially for process step (1). It is preferably an injection well and/or a production well which can also be used for process step (2) and/or has already been used in preceding water flooding.
- At least one production well and at least one injection well are sunk into the mineral oil deposit.
- a deposit is provided with several injection wells and with several production wells.
- Aqueous formulations can be injected into the mineral oil deposit through the at least one injection well, and the production wells serve to withdraw mineral oil from the mineral oil deposit.
- mineral oil in this context does not of course mean only single-phase oil, but instead the term also comprises the customary crude oil-water emulsions wherein the water may either be deposit water or injected water which has penetrated as far as the production well.
- the wells which can be used for process step (1) may preferably be the injection and/or production wells which are also used for process step (2).
- an aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer is used.
- the formulation may optionally comprise further components.
- hydrophobically associating copolymers is known in principle to those skilled in the art.
- hydrophobic groups comprise water-soluble copolymers which, as well as hydrophilic molecular components, have hydrophobic groups.
- hydrophobic groups can associate with themselves or with other substances having hydrophobic groups due to intermolecular forces. This gives rise to a polymeric network joined by intermolecular forces, which thickens the aqueous medium.
- the copolymers used in accordance with the invention should be miscible with water in any ratio. According to the invention, however, it is sufficient when the copolymers are water-soluble at least at the desired use concentration and at the desired pH. In general, the solubility in water at room temperature under the use conditions should be at least 35 WI.
- the water-soluble, hydrophobically associating copolymer used comprises 0.1 to 15% by weight of at least one monoethylenically unsaturated, hydrophobically associating monomer (a) and 85 to 99.9% by weight of at least two monoethylenically unsaturated, hydrophilic monomers (b) different than (a).
- ethylenically unsaturated, preferably monoethylenically unsaturated, monomers (c) different than the monomers (a) and (b) to be present in an amount of up to 14.9% by weight.
- the amounts mentioned are each based on the sum of all monomers in the copolymer. Preference is given to using exclusively monoethylenically unsaturated monomers.
- the water-soluble, hydrophobically associating copolymer used comprises at least one monoethylenically unsaturated monomer (a) which imparts hydrophobically associating properties to the copolymer and shall therefore be referred to hereinafter as “hydrophobically associating monomer”.
- the monomers (a) are selected from the group of
- an ethylenic group H 2 C ⁇ C(R 1 )— is bonded via a divalent linking group —R 2 —O— to a polyoxyalkylene radical with block structure —(—CH 2 —CH(R 3 )—O—) k —(—CH 2 —CH(R 4 )—O—) r —R 5 , where the two blocks —(—CH 2 —CH(R 3 )—O—) k and —CH 2 —CH(R 4 )—O—) l are arranged in the sequence shown in formula (I).
- the polyoxyalkylene radical has either a terminal OH group or a terminal ether group —OR 5 .
- R 1 is H or a methyl group.
- R 2 is a single bond or a divalent linking group selected from the group of —(C n H 2n )—[R 2a group], —O—(C n′ H 2n′ )—[R 2b group]- and —C(O)—O—(C n′′ H 2′′ )—[R 2c group].
- n, n′ and n′′ are each a natural number from 1 to 6.
- the linking group comprises straight-chain or branched aliphatic hydrocarbyl groups having 1 to 6 hydrocarbon atoms, which are joined to the ethylenic group H 2 C ⁇ C(R 1 )— directly, via an ether group —O— or via an ester group —C(O)—O—.
- the —(C n H 2n )—, —(C n′ H 2n′ )— and —(C n′′ H 2n′′ )— groups are preferably linear aliphatic hydrocarbyl groups.
- the R 2a group is preferably a group selected from —CH 2 —, —CH 2 —CH 2 — and —CH 2 —CH 2 —CH 2 —, more preferably a methylene group —CH 2 —.
- the R 2b group is preferably a group selected from —O—CH 2 —CH 2 —, —O—CH 2 —CH 2 —CH 2 — and —O—CH 2 —CH 2 —CH 2 —CH 2 —, more preferably —O—CH 2 —CH 2 —CH 2 —CH 2 —.
- the R 2c group is preferably a group selected from —C(O)—O—CH 2 —CH 2 —, —C(O)O—CH(CH 3 )—CH 2 —, —C(O)O—CH 2 —CH(CH 3 )—, —C(O)O—CH 2 —CH 2 —CH 2 —CH 2 — and —C(O)O—CH 2 —CH 2 —CH 2 —CH 2 —CH 2 —, more preferably —C(O)—O—CH 2 —CH 2 — and —C(O)O—CH 2 —CH 2 —CH 2 —CH 2 —, and most preferably —C(O)—O—CH 2 —CH 2 —.
- the R 2 group is more preferably an R 2a or R 2b group, more preferably an R 2b group.
- R 2 is more preferably a group selected from —CH 2 — and —O—CH 2 —CH 2 —CH 2 —CH 2 —, most preferably —O—CH 2 —CH 2 —CH 2 —CH 2 —.
- the monomers (I) also have a polyoxyalkylene radical which consists of the units —(—CH 2 —CH(R 3 )—O—) k and —(—CH 2 —CH(R 4 )—O—) l where the units are arranged in block structure in the sequence shown in formula (I). The transition between the two blocks may be abrupt or else continuous.
- the R 3 radicals are each independently H, methyl or ethyl, preferably H or methyl, with the proviso that at least 50 mol % of the R 3 radicals are H.
- the block mentioned is thus a polyoxyethylene block which may optionally also have certain proportions of propylene oxide and/or butylene oxide units, preferably a pure polyoxyethylene block.
- the number of alkylene oxide units k is a number from 10 to 150, preferably 12 to 100, more preferably 15 to 80, even more preferably 20 to 30 and, for example, approx. 22 to 25. It is clear to the person skilled in the art in the field of the polyalkylene oxides that the numbers mentioned are averages of distributions.
- the R 4 radicals are each independently hydrocarbyl radicals of at least 2 carbon atoms, preferably at least 3, more preferably 3 to 10 and most preferably 3 to 4 carbon atoms. This may be an aliphatic and/or aromatic, linear or branched carbon radical. It is preferably an aliphatic radical.
- R 4 radicals comprise ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl or n-decyl, and phenyl.
- suitable R 4 radicals comprise n-propyl, n-butyl, n-pentyl, particular preference being given to an n-propyl radical.
- R 4 radicals may also be ether groups of the general formula —CH 2 —O—R 4′ where R 4′ is an aliphatic and/or aromatic, linear or branched hydrocarbyl radical having at least 2 carbon atoms, preferably at least 3 and more preferably 3 to 10 carbon atoms.
- R 3′ radicals comprise n-propyl, n-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or phenyl.
- the —(—CH 2 —CH(R 4 )—O—) l — block is thus a block which consists of alkylene oxide units having at least 4 carbon atoms, preferably at least 5 carbon atoms, and/or glycidyl ethers having an ether group of at least 2, preferably at least 3, carbon atoms.
- Preferred R 3 radicals are the hydrocarbyl radicals mentioned; the units of the second terminal block are more preferably alkylene oxide units comprising at least 5 carbon atoms, such as pentene oxide units or units of higher alkylene oxides.
- the number of alkylene oxide units I is a number from 5 to 25, preferably 6 to 20, more preferably 8 to 18, even more preferably 10 to 15 and, for example, approx. 12.
- the R 5 radical is H or a preferably aliphatic hydrocarbyl radical having 1 to 30 carbon atoms, preferably 1 to 10 and more preferably 1 to 5 carbon atoms.
- R 5 is preferably H, methyl or ethyl, more preferably H or methyl and most preferably H.
- a terminal monoethylenic group is joined to a polyoxyalkylene group with block structure, specifically firstly to a hydrophilic block having polyethylene oxide units, which is in turn joined to a second terminal hydrophobic block formed at least from butene oxide units, preferably at least pentene oxide units, or units of higher alkylene oxides, for example dodecene oxide.
- the second block has a terminal —OR 5 -group, especially an OH-group.
- the terminal —(—CH 2 —CH(R 4 )—O—) l block with the R 4 radicals is responsible for the hydrophobic association of the copolymers prepared using the monomers (a).
- Etherification of the OH end group is an option which may be selected by the person skilled in the art according to the desired properties of the copolymer.
- a terminal hydrocarbyl group is, however, not required for the hydrophobic association, and the hydrophobic association also works with a terminal OH group.
- transition between the two blocks may be abrupt or else continuous.
- transition zone between the two blocks which comprises monomers of both blocks.
- the first block —(—CH 2 —CH(R 3 )—O—) k may accordingly also have small amounts of —CH 2 —CH(R 4 )—O— units and the second block —(—CH 2 —CH(R 4 )—O—) l — small amounts of —CH 2 —CH(R 3 )—O— units, though these units are not distributed randomly over the block but arranged in the transition zone mentioned.
- hydrophobically associating monomers (a) of the formula (I) can be prepared by methods known in principle to those skilled in the art.
- a preferred preparation process proceeds from suitable monoethylenically unsaturated alcohols (IV) which are subsequently alkoxylated in a two-stage process such that the block structure mentioned is obtained.
- These can optionally be etherified in a further process step.
- the type of ethylenically unsaturated alcohols (IV) to be used is guided here especially by the R 2 group.
- the starting materials are alcohols (IV) of the general formula H 2 C ⁇ C(R 1 )—O—(—CH 2 —CH(R 7 )—O—) d —H (IVa) where R 1 is as defined above, R 7 is H and/or CH 3 , preferably H, and d is a number from 1 to 5, preferably 1 or 2.
- Examples of such alcohols comprise diethylene glycol vinyl ether H 2 C ⁇ CH—O—CH 2 —CH 2 —O—CH 2 —CH 2 —OH or dipropylene glycol vinyl ether H 2 C ⁇ CH—O—CH 2 —CH(CH 3 )—O—CH 2 —CH(CH 3 )—OH, preferably diethylene glycol vinyl ether.
- the preparation of the monomers with a linking R 2a group preferably proceeds from alcohols of the formula H 2 C ⁇ C(R 1 )—(C n H 2n )—OH, especially H 2 C ⁇ CH—(C n H 2n )—OH, or alcohols of the formula H 2 C ⁇ C(R 1 )—O—(—CH 2 —CH(R 7 )—O—) d —H.
- preferred alcohols comprise allyl alcohol H 2 C ⁇ CH—CH 2 —OH or isoprenol H 2 C ⁇ C(CH 3 )—CH 2 —CH 2 —OH.
- the preparation of the monomers with a linking R 2b group proceeds from vinyl ethers of the formula H 2 C ⁇ C(R 1 )—O—(C n′ H 2n′ )—OH, preferably H 2 C ⁇ CH—O—(C n′ H 2n′ )—OH. It is more preferably possible to use w-hydroxybutyl vinyl ether H 2 C ⁇ CH—O—CH 2 —CH 2 —CH 2 —CH 2 —OH.
- the preparation of the monomers with a linking R 2 group proceeds from hydroxyalkyl (meth)acrylates of the general formula H 2 C ⁇ C(R 1 )—C(O)—O—(C n′′ H 2n′′ )—OH, preferably H 2 C ⁇ C(R 1 )—C(O)—O—(C n′′ H 2n′′ )—OH.
- Examples of preferred hydroxyalkyl (meth)acrylates comprise hydroxyethyl (meth)acrylate H 2 C ⁇ C(R 1 )—C(O)—O—CH 2 —CH 2 —OH and hydroxybutyl (meth)acrylate H 2 C ⁇ C(R 1 )—C(O)—O—CH 2 —CH 2 —CH 2 —OH.
- the starting compounds mentioned are alkoxylated, specifically in a two-stage process, first with ethylene oxide, optionally in a mixture with propylene oxide and/or butylene oxide, and in a second step with alkylene oxides of the general formula (Xa) or (Xb)
- R 4 in (Xa) and R 4′ in (Xb) are each as defined at the outset.
- the alkoxylates can be prepared, for example, by base-catalyzed alkoxylation.
- the alcohol used as the starting material can be admixed in a pressure reactor with alkali metal hydroxides, preferably potassium hydroxide, or with alkali metal alkoxides, for example sodium methoxide.
- alkali metal hydroxides preferably potassium hydroxide
- alkali metal alkoxides for example sodium methoxide.
- ethylene oxide optionally in a mixture with propylene oxide and/or butylene oxide, at temperatures of 60 to 180° C., preferably 130 to 150° C.
- the addition is typically effected within 2 to 5 h, though the invention should not be restricted thereto.
- the reaction mixture is appropriately allowed to continue to react, for example for 1 ⁇ 2 h to 1 h.
- alkylene oxides of the general formula (Xb) are subsequently metered in stepwise.
- the reaction temperature in the second stage can be maintained or else altered. A reaction temperature lower by approx. 10 to 25° C. than in the first stage has been found to be useful.
- the alkoxylation can also be undertaken by means of techniques which lead to narrower molecular weight distributions than the base-catalyzed synthesis.
- the catalysts used may, for example, be double hydroxide clays as described in DE 43 25 237 A1.
- the alkoxylation can more preferably be effected using double metal cyanide catalysts (DMC catalysts).
- DMC catalysts are disclosed, for example, in DE 102 43 361A1, especially paragraphs [0029] to [0041] and the literature cited therein.
- the alcohol used as the starting material can be admixed with the catalyst, and the mixture can be dewatered as described above and reacted with the alkylene oxides as described.
- the catalyst can remain in the product due to this small amount.
- the alkoxylation can additionally also be undertaken under acid catalysis.
- the acids may be Br ⁇ nsted or Lewis acids.
- the alcohol used as the starting material can be admixed with the catalyst, and the mixture can be dewatered as described above and reacted with the alkylene oxides as described.
- the acidic catalyst can be neutralized by addition of a base, for example KOH or NaOH, and filtered off if required.
- the orientation of the hydrocarbyl radicals R 4 and optionally R 3 may depend on the conditions of the alkoxylation, for example on the catalyst selected for the alkoxylation.
- the alkylene oxide groups can thus be incorporated into the monomer either in the —(—CH 2 —CH(R 4 )—O—) orientation or else in the inverse —(—CH(R 4 )—CH 2 —O—)— orientation.
- the description in formula (I) should therefore not be considered to be restricted to a particular orientation of the R 3 or R 4 groups.
- terminal OH group of the monomers (a) of the formula (I) i.e. R 5 ⁇ H
- this can be accomplished with customary alkylating agents known in principle to those skilled in the art, for example alkyl sulfates.
- alkyl sulfates For etherification, it is especially possible to use dimethyl sulfate or diethyl sulfate.
- the preferred preparation process described for the monomers (I) has the advantage that the formation of possibly crosslinking by-products is substantially avoided. Accordingly, it is possible to obtain copolymers with a particularly low gel content.
- R 1 , R 3 and k are each defined as already outlined.
- R 6 is an aliphatic and/or aromatic, straight-chain or branched hydrocarbyl radical having 8 to 40 carbon atoms, preferably 12 to 32 carbon atoms.
- it may comprise n-alkyl groups such as n-octyl, n-decyl or n-dodecyl groups, phenyl groups, and especially substituted phenyl groups.
- Substituents on the phenyl groups may be alkyl groups, for example C 1 -C 6 -alkyl groups, preferably styryl groups. Particular preference is given to a tristyrylphenyl group.
- hydrophobically associating monomers of the formulae (II) and (III) and the preparation thereof are known in principle to those skilled in the art, for example from EP 705 854 A1.
- the amount of the monoethylenically unsaturated, hydrophobically associating monomers (a) is 0.1 to 15% by weight, based on the total amount of all monomers in the copolymer, especially 0.1 to 10% by weight, preferably 0.2 to 5% by weight and more preferably 0.5 to 5% by weight and, for example, 0.5 to 2% by weight.
- the hydrophobically associating copolymer used in accordance with the invention comprises at least two monoethylenically unsaturated monomers (b) different than (a). referred to hereinafter as (b1) and (b2).
- the monomers (b1) are uncharged, hydrophilic monomers.
- the monomers (b2) are anionic, hydrophilic monomers (b2a) and/or (meth)acrylic esters (b2b).
- the (meth)acrylic esters themselves are, according to the nature of the ester group, generally not hydrophilic, but can be hydrolyzed under formation conditions to form hydrophilic groups.
- the hydrophilic monomers (b1) and (b2a) used are miscible with water in any ratio, but it is sufficient for execution of the invention that the inventive, hydrophobically associating copolymer possesses the water solubility mentioned at the outset.
- the solubility of the monomers (b1) and (b2a) in water at room temperature should be at least 50 g/l, preferably at least 150 g/l and more preferably at least 250 g/l.
- the copolymer comprises at least one uncharged, monoethylenically unsaturated, hydrophilic monomer (b1) selected from the group of (meth)acrylamide, N-methyl(meth)acrylamide, N,N′-dimethyl(meth)acrylamide or N-methylol(meth)acrylamide. Preference is given to (meth)acrylamide, especially acrylamide. When mixtures of different monomers (b1) are used, at least 50 mol % of the monomers (b1) should be (meth)acrylamide, preferably acrylamide.
- the copolymer used further comprises at least monomer (b2a) and/or (b2b).
- Monomer (b2a) comprises hydrophilic, monoethylenically unsaturated anionic monomers which have at least one acidic group selected from the group of —COOH, —SO 3 H and —PO 3 H 2 and salts thereof. Preference is given to monomers comprising COOH groups and/or —SO 3 H groups, particular preference to monomers comprising —SO 3 H groups.
- the monomers may of course also be the salts of the acidic monomers.
- Suitable counterions comprise especially alkali metal ions such as Li + , Na + or K + , and ammonium ions such as NH 4 + or ammonium ions with organic radicals.
- Examples of monomers comprising COOH groups comprise acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid. Preference is given to acrylic acid.
- Examples of monomers comprising sulfo groups comprise vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid or 2-acrylamido-2,4,4-trimethylpentanesulfonic acid.
- Examples of monomers comprising phospho groups comprise vinylphosphonic acid, allylphosphonic acid, N-(meth)acrylamidoalkylphosphonic acids or (meth)acryloyloxyalkyl-phosphonic acids, preference being given to vinylphosphonic acid.
- the monomers (b1) can be hydrolyzed at least partly to (meth)acrylic acid under some circumstances in the course of preparation and use of the copolymers.
- the hydrolysis can of course also be undertaken deliberately by the person skilled in the art.
- the copolymers used in accordance with the invention may accordingly comprise (meth)acrylic acid units, even if (meth)acrylic acid itself has not been used for the synthesis.
- the tendency to hydrolysis of the monomers (b1) decreases with increasing content of sulfo groups. Accordingly, the presence of sulfo groups in the copolymer used in accordance with the invention is advisable.
- the monomers (b2b) are (meth)acrylic esters of the general formula H 2 C ⁇ C(R 15 )—COOR 16 .
- R 16 may be methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, i-butyl, 1-pentyl, 1-hexyl, 1-heptyl or 1-octyl radicals.
- R 15 here is H or methyl, preferably H.
- R 16 is a straight-chain or preferably branched alkyl radical having 1 to 8 carbon atoms.
- R 16 is preferably a secondary alkyl radical —CH(R 17 )(R 17′ ), where R 17 and R 17′ are straight-chain or branched alkyl radicals, with the proviso that the total number of carbon atoms in the R 17 and R 17′ radicals is 2 to 7.
- Examples of such secondary alkyl radicals comprise 2-propyl, 2-butyl or 2-pentyl radicals.
- R 16 is a tertiary alkyl radical —C(R 18 )(R 18′ )(R 18′′ ), where R 18 , R 18′ , R 18′′ are straight-chain or branched alkyl radicals, with the proviso that the total number of carbon atoms in the R 18 , R 18′ and R 18′′ radicals is 3 to 7.
- a particularly preferred tertiary alkyl radical is a t-butyl radical —C(CH 3 ) 3 .
- ester groups of the (meth)acrylic esters (b2b) can, after being incorporated into the copolymer, be hydrolyzed to —COOH groups or salts thereof, especially under formation conditions, i.e. especially elevated temperature. This results in in situ formation of polymers comprising the units (b1) and (b2a). Esters having secondary and especially tertiary alkyl radicals are hydrolyzed more quickly than esters of primary alkyl radicals and are therefore particularly preferred.
- copolymers used in accordance with the invention may additionally optionally comprise at least one monoethylenically unsaturated, cationic monomer (b3) having ammonium ions.
- Suitable cationic monomers (b3) comprise especially monomers having ammonium groups, especially ammonium derivatives of N-(w-aminoalkyl)(meth)acrylamides or w-aminoalkyl-(meth)acrylic esters, and also diallyldimethylammonium salts.
- monomers (b3) having ammonium groups may be compounds of the general formulae H 2 C ⁇ C(R 8 )—CO—NR 9 —R 10 —NR 11 3 + X ⁇ (Va) and/or H 2 C ⁇ C(R 8 )—COO—R 10 —NR 11 3 + X ⁇ (Vb).
- R 8 is H or methyl
- R 9 is H or a C 1 -C 4 -alkyl group, preferably H or methyl
- R 10 is a preferably linear C 1 -C 4 -alkylene group, for example a 1,2-ethylene group —CH 2 —CH 2 — or a 1,3-propylene group —CH 2 —CH 2 —CH 2 —.
- the R 11 radicals are each independently C 1 -C 4 -alkyl radicals, preferably methyl, or a group of the general formula —R 12 —SO 3 H where R 12 is a preferably linear C 1 -C 4 -alkylene group or a phenyl group, with the proviso that generally not more than one of the R 11 substituents is a substituent having sulfo groups. More preferably, the three R 11 substituents are methyl groups, i.e. the monomer has a —N(CH 3 ) 3 + group.
- X ⁇ in the above formula is a monovalent anion, for example Cl ⁇ .
- X ⁇ may of course also be a corresponding fraction of a polyvalent anion, though this is not preferred.
- preferred monomers (b3) of the general formula (Va) or (Vb) comprise salts of 3-trimethylammoniopropyl(meth)acrylamides or 2-trimethylammonioethyl (meth)acrylates, for example the corresponding chlorides such as 3-trimethylammoniopropyl-acrylamide chloride (DIMAPAQUAT) and 2-trimethylammoniomethyl methacrylate chloride (MADAME-QUAT).
- the copolymers used in accordance with the invention may additionally also comprise further monoethylenically unsaturated hydrophilic monomers (b4) different than the hydrophilic monomers (b1), (b2) and (b3).
- monomers comprise monomers comprising hydroxyl groups and/or ether groups, for example hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, allyl alcohol, hydroxyvinyl ethyl ether, hydroxyvinyl propyl ether, hydroxyvinyl butyl ether, or compounds of the formula H 2 C ⁇ C(R 1 )—COO—(—CH 2 —CH(R 13 )—O—) b —R 14 (Vla) or H 2 C ⁇ C(R 1 )—O—(—CH 2 —CH(R 13 )—O—) b —R 14 (Vlb), where R 1 is as defined above and b is a number from 2 to 200, preferably 2 to 100.
- the R 13 radicals are each independently H, methyl or ethyl, preferably H or methyl, with the proviso that at least 50 mol % of the R 13 radicals are H. Preferably at least 75 mol % of the R 13 radicals are H, more preferably at least 90 mol %, and they are most preferably exclusively H.
- the R 14 radical is H, methyl or ethyl, preferably H or methyl.
- Further examples of monomers (b4) comprise N-vinyl derivatives, for example N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone or N-vinylcaprolactam, and vinyl esters, for example vinyl formate or vinyl acetate. N-Vinyl derivatives can be hydrolyzed after polymerization to give vinylamine units, and vinyl esters to give vinyl alcohol units.
- Copolymers used with preference comprise monomers (b1) and (b2a), but no monomers (b2b).
- copolymers used with preference comprise monomers (b1) and (b2b), but no monomers (b2a).
- ester groups of the monomers (b2b) it is also possible in this case for the ester groups of the monomers (b2b) to be hydrolyzed to —COOH groups, especially under formation conditions, and so such copolymers may also have —COOH groups some time after employment.
- the amount of all monomers (b) in the inventive copolymer is, in accordance with the invention, 85 to 99.9% by weight, based on the total amount of all monomers in the copolymer, preferably 90 to 99.8% by weight.
- the amount of the uncharged, hydrophilic monomers (b1) here is generally 30 to 95% by weight, preferably 30 to 85% by weight and more preferably 30 to 70% by weight, based on the total amount of all monomers used.
- the copolymer comprises only uncharged monomers (b1) and anionic monomers (b2a)
- the uncharged monomers (b1) in an amount of 30 to 95% by weight and the anionic monomers (b2a) in an amount of 4.9 to 69.9% by weight, each amount being based on the total amount of all monomers used.
- the monomers (b1) are preferably used in an amount of 30 to 80% by weight and the anionic monomers (b2a) in an amount of 19.9 to 69.9% by weight
- the monomers (b1) are more preferably used in an amount of 40 to 70% by weight and the anionic monomers (b2a) in an amount of 29.9 to 59.9% by weight.
- the copolymer comprises uncharged monomers (b1), anionic monomers (b2a) and cationic monomers (b3)
- the uncharged monomers (b1) in an amount of 30 to 95% by weight
- the anionic (b2a) and cationic (b3) monomers together in an amount of 4.9 to 69.9% by weight, with the proviso that the molar (b2a)/(b3) ratio is 0.7 to 1.3.
- the molar (b2a)/(b3) ratio is preferably 0.8 to 1.2 and, for example, 0.9 to 1.1. This measure makes it possible to obtain copolymers which are particularly insensitive to salt burden.
- the monomers (b1) are preferably used in an amount of 30 to 80% by weight, and the anionic and cationic monomers (b2a)+(b3) together in an amount of 19.9 to 69.9% by weight, and the monomers (b1) are more preferably used in an amount of 40 to 70% by weight and the anionic and cationic monomers (b2a)+(b3) together in an amount of 29.9 to 59.9% by weight, where the molar ratio already mentioned should be observed in each case.
- the amount of the monomers (b2b) is judged by the person skilled in the art such that the water solubility of the copolymer is not impaired by the use of the monomers (b2b).
- the amount of the monomers (b2b) should therefore generally, if present, not exceed 20% by weight, based on the total amount of all monomers.
- the amount should preferably not exceed 10% by weight. It may, for example, be 0.5 to 5% by weight.
- the inventive copolymers may optionally comprise ethylenically unsaturated monomers different than the monomers (a) and (b), preferably monoethylenically unsaturated monomers (c).
- ethylenically unsaturated monomers different than the monomers (a) and (b)
- monoethylenically unsaturated monomers c
- Such monomers can be used for fine control of the properties of the copolymer used in accordance with the invention. If present at all, the amount of such optionally present monomers (c) may be up to 14.9% by weight, preferably up to 9.9% by weight, more preferably up to 4.9% by weight, based in each case on the total amount of all monomers. Most preferably, no monomers (c) are present.
- the monomers (c) may, for example, be monoethylenically unsaturated monomers which have more hydrophobic character than the hydrophilic monomers (b1) and (b2a) and which are accordingly water-soluble only to a minor degree.
- the solubility of the monomers (c) in water at room temperature is less than 50 g/l, especially less than 30 g/l.
- Examples of such monomers comprise N-alkyl- and N,N′′-dialkyl(meth)acrylamides, where the number of carbon atoms in the alkyl radicals together is at least 3, preferably at least 4.
- Examples of such monomers comprise N-butyl(meth)acrylamide, N-cyclohexyl(meth)acrylamide or N-benzyl(meth)acrylamide.
- copolymers used in accordance with the invention can be prepared by methods known in principle to those skilled in the art, by free-radical polymerization of the monomers (a), (b) and optionally (c), for example by solution or gel polymerization in the aqueous phase.
- the monomers (a), (b), optionally (c), initiators and optionally further assistants for polymerization are used in an aqueous medium.
- the preparation is undertaken by means of gel polymerization in the aqueous phase.
- a mixture of the monomers (a), (b) and optionally (c), initiators and optionally further assistants with water or an aqueous solvent mixture is first provided.
- Suitable aqueous solvent mixtures comprise water and water-miscible organic solvents, where the proportion of water is generally at least 50% by weight, preferably at least 80% by weight and more preferably at least 90% by weight.
- Organic solvents in this context include especially water-miscible alcohols such as methanol, ethanol or propanol. Acidic monomers can be fully or partly neutralized before the polymerization.
- the concentration of all components except the solvents in the course of the polymerization is typically approx. 20 to 60% by weight, preferably approx. 30 to 50% by weight.
- the polymerization should especially be performed at a pH in the range from 5.0 to 7.5 and preferably at a pH of 6.0.
- the copolymers used are prepared in the presence of at least one nonpolymerizable, surface-active compound (T).
- the nonpolymerizable, surface-active compound (T) is preferably at least one nonionic surfactant, but anionic and cationic surfactants are also suitable to the extent that they do not take part in the polymerization reaction. They may especially be surfactants, preferably nonionic surfactants, of the general formula R 13 —Y′ where R 13 is a hydrocarbyl radical having 8 to 32, preferably 10 to 20 and more preferably 12 to 18 carbon atoms, and Y′ is a hydrophilic group, preferably a nonionic hydrophilic group, especially a polyalkoxy group.
- the nonionic surfactant is preferably an ethoxylated long-chain aliphatic alcohol which may optionally comprise aromatic components.
- Examples include: C 12 C 14 -fatty alcohol ethoxylates, C 16 C 18 -fatty alcohol ethoxylates, C 13 -oxo alcohol ethoxylates, C 10 -oxo alcohol ethoxylates, C 13 C 15 -oxo alcohol ethoxylates, C 10 -Guerbet alcohol ethoxylates and alkylphenol ethoxylates.
- Useful compounds have especially been found to be those having 5 to 20 ethyleneoxy units, preferably 8 to 18 ethyleneoxy units.
- alkyleneoxy units it is optionally also possible for small amounts of higher alkyleneoxy units to be present, especially propyleneoxy and/or butyleneoxy units, though the amount in the form of ethyleneoxy units should generally be at least 80 mol % based on all alkyleneoxy units.
- surfactants selected from the group of the ethoxylated alkylphenols, the ethoxylated, saturated iso-C13-alcohols and/or the ethoxylated C10-Guerbet alcohols, where in each case 5 to 20 ethyleneoxy units, preferably 8 to 18 ethyleneoxy units, are present in alkoxy radicals.
- the addition of nonpolymerizable, interface-active compounds (T) during the polymerization leads to a distinct improvement in performance properties of the copolymer in polymer flooding. More particularly, the thickening action is increased and the gel content of the copolymer is also reduced. This effect can probably be explained as follows, without any intention that the invention thus be tied to this explanation.
- the hydrophobically associating comonomers (a) form micelles in the aqueous reaction medium. In the polymerization, this leads to blockwise incorporation of the hydrophobically associating regions into the polymer.
- mixed micelles comprise polymerizable and nonpolymerizable components.
- the hydrophobically associating monomers are then incorporated in relatively short blocks.
- the number of these relatively short blocks is greater per polymer chain.
- the nonpolymerizable, interface-active compounds (T) can generally be used in an amount of 0.1 to 5% by weight, based on the amount of all monomers used.
- the weight ratio of the nonpolymerizable, interface-active compounds (T) used to the monomers (a) is generally 4:1 to 1:4, preferably 2:1 to 1:2, more preferably 1.5:1 to 1:1.5 and, for example, approx. 1:1.
- the components required are first mixed with one another.
- the sequence with which the components are mixed for polymerization is unimportant; what is important is merely that, in the preferred polymerization method, the nonpolymerizable, interface-active compound (T) is added to the aqueous polymerization medium before the initiation of the polymerization.
- the mixture is subsequently polymerized thermally and/or photochemically, preferably at ⁇ 5° C. to 80° C.
- polymerization initiators which can initiate the polymerization even at comparatively low temperature, for example redox initiators.
- the thermal polymerization can be undertaken even at room temperature or by heating the mixture, preferably to temperatures of not more than 50° C.
- the photochemical polymerization is typically undertaken at temperatures of ⁇ 5 to 10° C. It is also possible to combine photochemical and thermal polymerization with one another, by adding both initiators for the thermal and photochemical polymerization to the mixture. In this case, the polymerization is first initiated photochemically at low temperatures, preferably ⁇ 5 to +10° C. The heat of reaction released heats the mixture, which additionally initiates the thermal polymerization. By means of this combination, it is possible to achieve a conversion of more than 99%.
- the reaction it is also possible to perform the reaction with a mixture of a redox initiator system and a thermal initiator which does not decompose until relatively high temperatures.
- a thermal initiator which does not decompose until relatively high temperatures.
- This may, for example, be a water-soluble azo initiator which decomposes within the temperature range from 40° C. to 70° C.
- the polymerization here is at first initiated at low temperatures of, for example, 0 to 10° C. by the redox initiator system. The heat of reaction released heats the mixture, and this additionally initiates the polymerization by virtue of the initiator which does not decompose until relatively high temperatures.
- the gel polymerization is generally effected without stirring. It can be effected batchwise by irradiating and/or heating the mixture in a suitable vessel at a layer thickness of 2 to 20 cm. The polymerization gives rise to a solid gel.
- the polymerization can also be effected continuously.
- a polymerization apparatus possessing a conveyor belt to accommodate the mixture to be polymerized is used.
- the conveyor belt is equipped with devices for heating and/or for irradiating with UV radiation.
- the mixture is poured onto one end of the belt by means of a suitable apparatus, the mixture is polymerized in the course of transport in belt direction, and the solid gel can be removed at the other end of the belt.
- the gel obtained is preferably comminuted and dried after the polymerization.
- the drying should preferably be effected at temperatures below 100° C.
- a suitable separating agent for this step. This gives the hydrophobically associating copolymer as granules or powder.
- the polymer powder or granules obtained are generally used in the form of an aqueous solution in the course of application at the site of use, the polymer has to be dissolved in water on site. This may result in undesired lumps with the high molecular weight polymers described.
- an assistant which accelerates or improves the dissolution of the dried polymer in water to the inventive polymers as early as in the course of synthesis.
- This assistant may, for example, be urea.
- the resulting copolymers preferably have a weight-average molecular weight M w of 1*10 6 g/mol to 30*10 6 g/mol, preferably 5*10 6 g/mol to 20*10 6 g/mol.
- an aqueous formulation which comprises, in addition to water, at least the hydrophobically associating copolymer described is used. It is of course also possible to use mixtures of different hydrophobically associating copolymers.
- the formulation may also comprise water-miscible organic solvents, in which case the amount of the water should generally comprise at least 75% by weight, preferably at least 90% by weight and more preferably at least 95% by weight based on the sum of all solvents used. Very particular preference is given to using exclusively water as the solvent.
- the formulation can be made up in freshwater or else in water comprising salts.
- the formulation can preferably be prepared by initially charging the water, sprinkling in the copolymer as a powder and mixing it with the water, and is preferably made up at ambient temperature.
- the concentration of the polymer in the formulation is 0.1 to 3% by weight based on the sum of all components of the aqueous formulation.
- the amount is preferably 0.5 to 3% by weight and more preferably 1 to 3% by weight.
- the concentration of the copolymer and hence the viscosity of the formulation used can be determined by the person skilled in the art according to the conditions in the formation.
- the formulation may optionally comprise further components, for example crosslinkers, biocides, stabilizers or salts.
- Further components may especially be water-soluble crosslinkers which can bring about crosslinking of the hydrophobically associating copolymer under deposit conditions.
- Crosslinkers may, for example, be water-soluble compounds comprising di-, tri- or tetravalent metal ions, for example compounds comprising Al(III), Cr(III) or Zr(IV) ions, for example chromium(III) acetate, aluminum(III) citrate, zirconium(IV) salts such as zirconium(IV) lactate or zirconium(IV) acetate.
- the crosslinkers may also be boric acid or salts thereof.
- the crosslinkers may also be organic crosslinkers, for example aldehydes such as formaldehyde, glyoxal or glutaraldehyde, or organic compounds comprising at least two amino or ammonium groups, for example polyethyleneimines, polyvinylamine or polyetheramines.
- the crosslinkers may also be microencapsulated crosslinkers in which the crosslinker is released only after the injection of the formulation into the formation.
- the amounts of crosslinker are selected by the person skilled in the art according to the desired properties, for example the desired degree of crosslinking.
- the amount of crosslinker may, for example, be 1 to 10% by weight based on the amount of the polymer used.
- the performance of process step (1) involves injecting the above-described aqueous formulation which comprises at least the hydrophobically associating copolymer described into the formation through at least one well.
- Process step (1) can be executed as the first process step, and then process step (2) of the process according to the invention.
- Process step (1) can, however, also be executed only after a first performance of process step (2), especially after water flooding of the formation. This variant is advisable when water production has already risen significantly as a result of sustained water flooding.
- the injection of the aqueous formulation can be undertaken by means of customary apparatus.
- the formulation can be injected by means of customary pumps.
- the wells are typically lined with cemented steel pipes, and the steel pipes are perforated at the desired site.
- the formulation enters the mineral oil formation through the perforation in the well.
- the pressure applied by means of the pumps fixes the flow rate of the formulation and hence also the shear stress with which the aqueous formulation enters the deposit.
- the process may of course also be performed when the well has not been lined.
- suitable copolymers According to the type of underground formation and the regions to be blocked, a person skilled in the art selects suitable copolymers.
- the formation of a gel in the underground formation can, according to the copolymer, proceed with use of crosslinkers or else without the use of crosslinkers.
- copolymers used in accordance with the invention as a constituent of the aqueous formulation are notable for thermal thickening characteristics within particular temperature ranges, which means that the aqueous formulations are notable in that the viscosity thereof at room temperature is lower than at higher temperatures. In general, the viscosity passes through a maximum in the range from approx. 50 to 80° C. The details on this subject are given in the experimental section.
- Preferred copolymers for this application comprise, as well as the monomers (a) and (b1), monomers (b2a) having sulfo groups. These may more preferably be copolymers comprising monomers (a), acrylamide and 2-acrylamido-2-methylpropanesulfonic acid.
- permeable regions of the formation can therefore be blocked by exploiting the thermal thickening characteristics of the copolymers used.
- no crosslinker need be added to the formulation.
- the temperature of the aqueous formulation before the injection should preferably be lower than the deposit temperature.
- “Before the injection” relates to the temperature of the formulation at the surface of the earth before it is injected into the well.
- the temperature of the aqueous formulation before the injection into the deposit is preferably less than 35° C., more preferably less than 30° C. and, for example, approx. 15° C. to 25° C.
- the temperature of the aqueous formulation of the hydrophobically associating copolymer is lower than the deposit temperature.
- the aqueous formulation After entry into the mineral oil formation, the aqueous formulation naturally flows into the permeable regions of the formation with low flow resistance. Under the influence of the deposit temperature, the aqueous formulation heats up to an increasing degree and accordingly gradually increases in viscosity until ultimate formation of a gel which has such a high viscosity that the permeable regions of the formation are blocked.
- This variant is suitable especially for formations with a deposit temperature of more than 40° C., preferably more than 45° C., especially 40° C. to 100° C., preferably 45° C. to 90° C., more preferably 50° C. to 75° C.
- the temperature of the aqueous formulation before injection into the deposit should be at least 10° C., preferably at least 20° C., lower than the deposit temperature.
- hydrophobically associating copolymers used in accordance with the invention especially the already mentioned copolymers comprising monomers (a), (b1) and (b2a) also have shear-diluting characteristics, i.e. the viscosity thereof decreases with increasing shear. It is therefore advisable to inject the aqueous formulations with high flow rate. This retards the heating of the formulation, but the shear-diluting characteristics do not result in mechanical degradation of the copolymer on entry into the formation, and so it regains viscosity after the shear has declined.
- the shear rate on entry of the aqueous copolymer formulation into the formation is therefore at least 30 000 s ⁇ 1 , preferably at least 60 000 s ⁇ 1 and more preferably at least 90 000 s ⁇ 1 .
- the shear stress on entry into the formation can be calculated by the person skilled in the art in a manner known in principle on the basis of the Hagen-Poiseuille law using the area flowed through on entry into the formation, the mean pore radius and the volume flow rate.
- the average porosity of the formation can be calculated in a manner known in principle by measurements on drill cores. The greater the volume flow rate of aqueous formulation injected into the formation, the greater the shear stress will naturally be.
- Copolymers particularly preferred for execution of the outlined embodiments 1 and 2 of the process comprise monomers (a) of the general formula H 2 C ⁇ CH—O—(CH 2 ) n′ —O—(—CH 2 —CH 2 —O—) k —(—CH 2 —CH(R 4 )—O—) l —H (Ia) where n′ is 2 to 6, preferably 2 to 4 and more preferably 4.
- R 4 in the preferred variant is a hydrocarbyl radical having 3 to 10 carbon atoms, especially an n-propyl radical.
- k is a number from 20 to 30 and I is a number from 6 to 20, preferably 8 to 18.
- the amount of the monomers (a) of the formula (Ia) is 0.2 to 5% by weight, preferably 0.5 to 2% by weight.
- the copolymer preferred for embodiments 1 and 2 comprises 40 to 60% by weight of acrylamide, and as monomer (b2a) 35 to 55% by weight of a monomer (b2a) having sulfo groups, preferably 2-acrylamido-2-methylpropane-sulfonic acid or salts thereof.
- Particular preference is given to using exclusively monomers (b2a) having sulfo groups.
- a formulation which additionally comprises one or more crosslinkers which can bring about the crosslinking of the polymer under deposit conditions is used.
- the crosslinking reaction thus occurs only in the course of heating of the formulation to deposit temperature.
- the above-described crosslinkers can be used in the aqueous formulation.
- the crosslinking of the polymer improves the strength of the gel for blockage of the formation.
- the copolymers particularly suitable for embodiments 1 and 2 can be used with preference.
- copolymers having COOH groups or those which form COOH groups under formation conditions.
- Copolymers which are particularly advantageous for this third embodiment are therefore those which comprise monomers (a), (b1) and (b2b). Preference is given especially to copolymers comprising monomers (a) of the general formula H 2 C ⁇ CH—O—(CH 2 ) n′ —O—(—CH 2 —CH 2 —O—) k —(—CH 2 —CH(R 4 ) l —H (Ia). Preferred ranges for n′, k, l and R 4 have already been specified above.
- (b1) is preferably acrylamide
- (b2b) especially comprises readily hydrolyzable esters with secondary or tertiary ester groups, especially t-butyl (meth)acrylate. Preferred amounts are 0.2 to 5% by weight of monomers (Ia), 70 to 99.7% by weight of (b1) and 0.1 to 10% by weight, preferably 0.2 to 5% by weight, of (b2b).
- crosslinking reactions do not proceed at a significant rate at room temperature, but only at higher temperatures, especially at temperatures of >50° C.
- —CONR'2 and/or —COOR 16 groups present in the polymer can be hydrolyzed to —COOH groups, and the —COOH groups of different copolymer chains can crosslink with one another via complexation with metal ions present in the formulation. It is likewise possible for COOH groups to react with polyethyleneimines and/or forms salts, and thus crosslink the copolymers.
- the crosslinking forms a high-viscosity gel which blocks the formation.
- copolymers which also comprise cationic monomers (b3) as well as monomers (b1) and (b2a) are used in the aqueous formulation.
- Preferred copolymers for this fourth embodiment comprise 0.2 to 5% by weight, preferably 0.5 to 2% by weight, of monomers (a) of the general formula (Ia), and, as monomers (b1), 30 to 40% by weight of acrylamide.
- They additionally comprise 25 to 35% by weight of at least one monomer (b2a) having sulfo groups, preferably 2-acrylamido-2-methylpropanesulfonic acid or salts thereof, and 25 to 35% by weight of at least one cationic monomer having ammonium ions, preferably salts of dialkyldiallylammonium, 3-trimethylammoniopropyl(meth)acrylamides and 2-trimethylammonioethyl (meth)acrylates.
- monomer (b2a) having sulfo groups preferably 2-acrylamido-2-methylpropanesulfonic acid or salts thereof
- at least one cationic monomer having ammonium ions preferably salts of dialkyldiallylammonium, 3-trimethylammoniopropyl(meth)acrylamides and 2-trimethylammonioethyl (meth)acrylates.
- This embodiment can be used, for example, in silicatic formations, especially sandstone formations. However, it can of course also be used in other formations, for example carbonatic formations.
- Silicatic formations have anionic sites on the surface, which can interact well with the cationic sites of the copolymers used. It is thus possible to form a polymer film on the surface of the rock formation, which constricts free cross sections. Further polymer can be absorbed on the polymer-modified surface.
- this embodiment can also be combined with crosslinking of the copolymer. For this purpose, the crosslinkers already outlined can be used.
- the injection of the copolymer used in accordance with the invention is preceded by injection of an aqueous formulation of a polymer having cationic groups.
- suitable cationic polymers comprise poly(diallyldimethyl-ammonium chloride), poly(N-acrylamidopropyl-N,N,N-trimethylammonium chloride) or poly(N-methacrylatopropyl-N,N-dimethyl-N-benzylammonium chloride), or corresponding copolymers, for example with acrylamide as a comonomer.
- the aqueous formulation of the copolymer used in accordance with the invention is injected into the formation, and the surface is cationically modified as a result.
- the copolymer which has anionic groups and is used in accordance with the invention can be adsorbed efficiently on the cationically modified surface.
- the injection of aqueous formulations of a cationic polymer and of the copolymer used in accordance with the invention can be repeated once or more than once. In this way, a multilayer polymer film of ever greater thickness forms on the formation surface.
- the aqueous copolymer formulation can be injected either through one or more injection wells and/or one or more production wells. This is guided by the specific conditions in the formation.
- Injection into a production well is particularly advisable, for example, when a water-bearing stratum is arranged below a mineral oil-bearing stratum, and water is increasingly being produced from the water-bearing stratum.
- the injection of aqueous flooding media into the injection wells is generally stopped. Measures known in principle to those skilled in the art can ensure that the aqueous copolymer formulation is actually injected into the water-bearing zone and not into the oil-bearing zone.
- steel pipes perforated exactly in the region of the water-bearing stratum can inject the copolymer formulation into the water-bearing stratum in a controlled manner.
- the penetration of polymer formulation into the oil-bearing stratum can be prevented by simultaneously injecting an inert protection fluid into the oil-bearing stratum.
- the aqueous copolymer formulation naturally flows into the permeable regions of the formation with low flow resistance, and hence exactly through the regions which are to be blocked.
- process step (2) mineral oil is actually produced by injection of an aqueous flooding medium into the at least one injection well and withdrawing mineral oil through the at least one production well.
- the aqueous flooding medium injected maintains the pressure and forces the mineral oil from the injection wells in the direction of the production wells.
- the aqueous flooding medium may preferably be water or salt-containing water.
- the process is called “water flooding”. It is possible to inject either freshwater or saltwater.
- seawater can be used for injection, for example in the case of production platforms, or it is possible to use produced formation water, which is reused in this manner. It may be cold water or hot water.
- the aqueous flooding media may, however, also be steam (“steam flooding”), aqueous formulations comprising surfactants (“surfactant flooding”) or formulations comprising thickening polymers (“polymer flooding”).
- the aqueous flooding media used in each case may be identical aqueous flooding media or have different compositions.
- step (1) When step (1) is executed by injection into the injection wells, it is advisable to commence the process with the performance of step (1). This is followed by process step (2). If process step (2) has formed new preferential flow paths, these can be blocked by repetition of step (1), followed by continuation with step (2). It will be appreciated that it is also possible to repeat the sequence of steps (1) and (2) several times.
- the blocking of permeable regions from the production well can advantageously be performed when water production has risen, i.e. after a first performance of process step (2). After the performance of process step (1), mineral oil production is repeated with the new performance of process step (2).
- a 1 l stirred stainless steel autoclave is initially charged with 44.1 g of hydroxybutyl vinyl ether. Subsequently, 3.12 g of KOMe (32% in MeOH) are metered in and the methanol is drawn off at 80° C. and approx. 30 mbar. This is followed by heating to 140° C., purging of the reactor with nitrogen and establishment of a nitrogen pressure of 1.0 bar. Then 368 g of EO are metered in within approx. 3 h. After continued reaction at 140° C. for a half hour, the reactor is cooled to 125° C., and a total of 392 g of pentene oxide are metered in over the course of 3.5 h. The reaction continues overnight.
- the product has an OH number of 31.9 mg KOH/g (theory: 26.5 mg KOH/g).
- the OH number is determined by means of the ESA method.
- a plastic bucket with magnetic stirrer, pH meter and thermometer is initially charged with 121.2 g of a 50% aqueous solution of NaATBS (2-acrylamido-2-methylpropanesulfonic acid, sodium salt), and then 155 g of distilled water, 0.6 g of a defoamer (Surfynol® DF-58), 0.2 g of a silicone defoamer (Baysilon® EN), 2.3 g of monomer M1, 114.4 g of a 50% aqueous solution of acrylamide, 1.2 g of pentasodium diethylenetriaminepentaacetate (complexing agent, as a 5% aqueous solution) and 2.4 g of a nonionic surfactant (nonylphenol, alkoxylated with 10 units of ethylene oxide) are added successively.
- the monomer solution After adjusting the pH with a 20% or 2% sulfuric acid solution to a value of 6 and adding the rest of the water, the monomer solution is adjusted to the start temperature of 5° C.
- the total amount of water is such that—after the polymerization—a solids concentration of approx. 30 to 36% by weight is attained.
- the solution is transferred to a thermos flask, a temperature sensor for the temperature recording is provided and the solution is purged with nitrogen for 30 minutes.
- the polymerization is then initiated by adding 1.6 ml of a 10% aqueous solution of a water-soluble cationic azo initiator 2,2′-azobis(2-amidinopropane) dihydrochloride (Wako V-50), 0.12 ml of a 1% aqueous solution of tert-butyl hydroperoxide and 0.24 ml of a 1% sodium sulfite solution.
- the temperature rises to approx. 80° C. within 15 to 30 min.
- the reaction vessel is placed into a drying cabinet at approx. 80° C. for approx. 2 h to complete the polymerization.
- the total duration of the polymerization is approx. 2 h to 2.5 h.
- a gel block is obtained, which, after the polymerization has ended, is comminuted with the aid of a meat grinder.
- the gel granules obtained are dried in a fluidized bed dryer at 55° C. for two hours. This gives white, hard granules which are converted to a pulverulent state by means of a centrifugal mill. This gives a copolymer with a weight-average molecular weight of approx. 1*10 6 g/mol to 30*10 6 g/mol.
- a 2 l three-neck flask with stirrer and thermometer was initially charged with 337.5 g of water. 0.06 g of sodium hypophosphite, 0.5 g of ammonium persulfate and 7.46 g of butyl acrylate were added successively to the reaction flask. Then it was purged with nitrogen for 45 min.
- a monomer solution consisting of 91.2 g of water, 272.56 g of 50 percent aqueous acrylamide solution, 1.03 g of 50 percent aqueous Trilon C solution, 2.93 g of monomer M1, 1.03 g of sodium dodecylsulfate, 0.1 g of sodium hypophosphite and 0.5 g of potassium bromate was prepared.
- Polymer 3 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
- Polymer 4 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
- Polymer 5 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
- a 2 l jacketed reactor with stirrer and water separator is initially charged with 600 g of Exxsol D40, 4 g of a 25 percent solution of a polymeric stabilizer for water-in-oil suspensions are added and the mixture is heated to 35° C. In the course of which, inertization is effected by purging with nitrogen for 90 min.
- 310.40 g of a 50 percent aqueous acrylamide solution, 18.05 g of a 35 percent sodium acrylate solution, 0.6 g of a 50 percent aqueous Trilon C, 0.81 g of monomer 1 and 10.12 g of water are mixed. 10 percent sulfuric acid is used to adjust the pH to 6.0.
- Polymer 7 was prepared like polymer 6, except that the amounts of the monomers were altered as follows:
- Polymer 8 was prepared like polymer 6, except that the amounts of the monomers were altered as follows:
- Polymer 9 was prepared like polymer 26, except that the amounts of the monomers were altered as follows:
- Polymer C2 was prepared like polymer 6 (suspension polymerization), except that the abovementioned monomers were used in the amounts specified.
- Solutions of polymers 1 and Cl were made up in a concentration of in each case 1200 ppm in tap water, and the viscosity of each of the solutions was measured at 30° C., 60° C., 90° C. and 120° C.
- FIG. 1 shows the result of the viscosity measurements.
- the viscosity of the polymer used in accordance with the invention rises with rising temperature up to a viscosity maximum at 60° C. and then decreases again, while the comparative polymer has a falling viscosity with rising temperature.
- the polymer used in accordance with the invention can thus be injected into the mineral oil formation low temperatures, and follows the preferred flow paths. The viscosity increases in the course of heating under the sole influence of the deposit temperature and thus leads to the formation of a highly viscous gel in the flow paths.
- inventive polymer 1 in tap water was prepared. This solution was highly viscous but still free-flowing at room temperature, especially at high shear rates as occur in the course of pumping of the polymer solution. In the course of heating to 60° C. at a low shear rate, the viscosity of the polymer solution rose significantly and it was barely free-flowing any longer.
- Brookfield viscosity (in mPas) of solutions of 0.5% by weight of polymers 10 to 13 and C2 and C3 in fresh water and in a salt solution was measured at various temperatures.
- the salt solution had the following composition:
- Comparative polymers C2 and C3 have only very low viscosities in salt water, and the viscosities decrease in the course of heating. Due to these properties, the polymers are outstandingly suitable for blocking of underground formations. The polymers can be injected efficiently at low viscosities and the viscosity increases very significantly underground.
- gel formulation was studied in seawater at 80° C.
- the combination of 80° C. and salt-containing water simulates the conditions in a typical mineral oil deposit.
- the t-butyl ester units of copolymers 2 to 5 are hydrolyzed to an extent of approx. 50% at 80° C. in seawater within 2 h, and form COOH groups.
- a synthetic seawater of the following composition was used:
- crosslinkers were added in some experiments.
- the crosslinkers used were:
- the gel appears to have the same viscosity (fluidity) as the original polymer solution, and no gel can be discovered visually.
- D moderately flowing gel.
- a small amount ( ⁇ 5-15%) of the gel flows into the bottle lid and back, usually characterized as a ‘tonguing’ gel (i.e. once the gel hangs out of the bottle, it can flow back into the bottle when the bottle is slowly turned upright).
- E barely flowing gel.
- the gel flows slowly into the bottle lid and/or a significant portion (>15%) of the gel does not flow into the bottle lid and back.
- F highly deformable gel. The gel does not flow into the bottle lid and back (gel barely flows to reach the bottle lid).
- G Moderately deformable non-flowing gel. Half of the gel flows to the bottle lid and back.
Abstract
Description
- This application claims benefit (under 35 USC 119(e)) of U.S. Provisional Application 61/473,190, filed Apr. 8, 2011, which is incorporated by reference.
- The present invention relates to a process for producing mineral oil from underground formations, wherein, in one process step, permeable regions of the underground formation are blocked by injecting aqueous formulations of hydrophobically associating copolymers into the formation.
- In natural mineral oil deposits, mineral oil occurs in the cavities of porous reservoir rocks which are closed off from the surface of the earth by impervious covering layers. The cavities may be very fine cavities, capillaries, pores or the like. Fine pore necks may, for example, have a diameter of only approx. 1 μm. The underground formation may additionally also have regions with pores of greater diameter and/or natural fractures. In addition to mineral oil, including proportions of natural gas, a deposit generally comprises water with a greater or lesser salt content.
- After a well has been sunk into the oil-bearing strata, mineral oil at first flows to the production wells owing to the natural deposit pressure, and is flushed to the surface of the earth. This phase of mineral oil production is known by the person skilled in the art as primary production. However, flush production generally ceases very rapidly, especially under poor deposit conditions, for example a high oil viscosity, rapidly declining deposit pressure or high flow resistances in the oil-bearing strata. With primary production, it is possible to produce an average of only 2 to 10% of the oil originally present in the deposit. In the case of higher-viscosity mineral oils, flush production is generally completely impossible.
- In order to enhance the mineral oil yield, what are known as secondary and optionally tertiary production processes are therefore used.
- One secondary mineral oil production process is called “water flooding”. For this purpose, the deposit is provided with one or more injection wells in addition to the production wells, i.e. the wells through which mineral oil is withdrawn from the mineral oil formation. Water is injected into the oil-bearing strata through the injection wells. This artificially increases the deposit pressure and forces the oil from the injection wells in the direction of the production wells. Water flooding can significantly enhance the exploitation level. Instead of water, it is also possible to inject steam into the deposit (“steam flooding”). This is advisable especially when the deposit comprises high-viscosity oils.
- In the course of water flooding, in the ideal case, a water front proceeding from the injection well should force the oil homogeneously over the entire mineral oil formation to the production well. In practice, a mineral oil formation, however, has regions with different levels of flow resistance. In addition to fine-porosity, oil-saturated reservoir rocks with a high flow resistance to water, there also exist regions with a low flow resistance to water, for example natural or synthetic fractures or very permeable regions in the reservoir rock. The permeable regions may also be already exploited regions. In the course of water flooding, the flooding water injected naturally flows principally through flow paths with low flow resistance from the injection well to the production well, while there is at least slower flow, if any, of water through the fine-porosity, oil-saturated deposit regions with high flow resistance. The water thus no longer flows homogeneously through the formation, and the water front is instead very irregular (called “fingering”), and an increasing amount of water and a decreasing amount of mineral oil are produced via the production well. In this connection, the person skilled in the art refers to “watering out of production”. The effects mentioned are particularly marked in the case of heavy and viscous mineral oils. The higher the mineral oil viscosity, the more probable is rapid watering out of production. The problem occurs especially in the presence of fissured rock formations (called “fractured reservoirs”).
- There also exist mineral oil formations in which a water-bearing stratum is arranged below an oil-bearing stratum. In the course of drilling into such a formation, not only mineral oil but also water is produced, and so production here too is significantly watered out.
- There has been no lack of attempts to prevent the inhomogeneous flow of water, or at least to achieve more homogeneous flow. In the prior art, there are therefore known measures for closing such highly permeable zones between the injection wells and production wells by means of suitable measures, or at least for reducing the permeability thereof. As a result, the flooding water or flooding steam is forced again to flow through the oil-saturated, low-permeability strata, and further mineral oil can thus again be mobilized. Such measures are also known as “conformance control” or “water shut-off”. An overview of conformance control measures is given by Boiling et al. “Pushing out the oil with Conformance Control” in Oilfield Review (1994), pages 44 ff.
- For blocking of highly permeable regions of underground formations, i.e. for conformance control, it is possible to use comparatively low-viscosity formulations of particular chemical substances which can be injected readily into the formation, and the viscosity of which rises significantly only after injection into the formation, under the conditions which exist in the formation. Such formulations comprise inorganic, organic or polymeric components suitable for increasing viscosity. The rise in viscosity of the injected formulation can occur, for example, with a simple time delay, and/or the rise in viscosity can be triggered by the temperature rise when the injected formulation in the deposit gradually heats up to the deposit temperature. Formulations whose viscosity rises only under formation conditions are known, for example, as “thermogels” or “delayed gelling systems”.
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SU 1 654 554 A1 discloses a process for producing oil using mixtures of aluminum chloride or aluminum nitrate, urea and water, which are injected into the mineral oil formation. The formulations naturally flow preferably along the flow paths with the lowest flow resistance. At the elevated temperatures in the formation, the urea is hydrolyzed to carbon dioxide and ammonia. The release of the ammonia base significantly increases the pH of the water, and a high-viscosity gel of aluminum hydroxide precipitates out, which blocks the highly permeable zones. - US 2008/0035344 A1 discloses a mixture for blocking of underground formations with retarded gelation, which comprises at least one acid-soluble, crosslinkable polymer, for example partly hydrolyzed polyacrylamide, a partly neutralized aluminum salt, for example an aluminum hydroxide chloride, and an activator which can release bases under formation conditions, for example urea, substituted ureas or hexamethylenetetramine. The mixture can preferably be used at a temperature of 0 to 40° C. and gelates at temperatures above 50° C., according to the use conditions, within 2 h to 10 days.
- RU 2 361 074 discloses a process for blocking highly permeable zones, in which portions of formulations based on urea and aluminum salts are injected into a deposit with high deposit temperature.
- U.S. Pat. No. 4,182,417, US 2007/0204989, WO 2007/126318 A1 and WO 2010/069607 A1 disclose water-swellable particles for blocking of underground formations. These particles can be injected in a suitable formulation into the underground formation, swell in the formation under the influence of the formation water and in this manner block highly permeable regions of the formation.
- R. D. Sydansk “Acrylamide-Polymer/Chromium(III)-Carboxylate Gels for Near Wellbore Matrix Treatments” in Proceedings Society of Petroleum Engineers/US Department of Energy, 7th Symposium on Enhanced Oil Recovery, Apr. 22-25, 1990, Tulsa, Okla., SPE/DOE 20214, Society of Petroleum Engineers, 1990 disclose acrylamide-chromium(III) carboxylate gels for blocking of underground formations. For this purpose, acrylamide and Cr(III) carboxylates, for example Cr(III) acetate, are injected into the formation. Under the formation conditions, amide groups of the polymer are hydrolyzed to carboxylate groups. The Cr(III) carboxylate then crosslinks carboxylate groups of different polymer strands, thus forming a viscous gel.
- U.S. Pat. No. 4,613,631 discloses gels formed from crosslinked polymers for blocking of underground formations. The polymers may, for example, be polyacrylamide, polyacrylic acids, or else biopolymers, for example xanthogenates. The crosslinkers used are organic compounds which have at least two positively charged nitrogen atoms.
- U.S. Pat. No. 7,150,319 B2 discloses a process for blocking underground formations, in which a copolymer comprising 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, a further nitrogen-containing monomer, for example N-vinylformamide or N-vinylpyrrolidone, and vinylphosphonic acid as monomers. The copolymer is crosslinked with compounds of chromium, zirconium, titanium or aluminum to form a viscous gel.
- U.S. Pat. No. 6,803,348 B2 discloses a process for reducing water production from mineral oil-bearing underground formations, in which water-soluble, hydrophobically associating copolymers comprising a linear hydrophilic main chain, hydrophobic side groups and functional groups which can be used for crosslinking are used. The water-soluble copolymers are injected into the underground formation and crosslinked therein, for example by means of Cr(III) ions, Zr(IV) ions or aldehydes. The polymers are preferably based on polyacrylamides. The hydrophobic groups are preferably alkyl groups having at least 6, preferably at least 8 and more preferably at least 12 carbon atoms. The copolymer may comprise, for example, N-alkylacrylamides, for example N-decylacrylamide, as a monomer.
- WO 2010/133527 A2 discloses hydrophobically associating copolymers which comprise at least hydrophilic, monoethylenically unsaturated monomers, for example acrylamide, and monoethylenically unsaturated, hydrophobically associating monomers. The hydrophobically associating monomers have a block structure and have—in this sequence—an ethylenically unsaturated group, optionally a linking group, a first polyoxyalkylene block which comprises at least 50 mol % of ethyleneoxy groups, and a second polyoxyalkylene block which consists of alkyleneoxy groups having at least 4 carbon atoms. The application discloses the use of such copolymers as thickeners, for example for polymer flooding, for construction chemical applications, or for detergent formulations.
- WO 2011/015520 A1 discloses a process for preparing hydrophobically associating copolymers by polymerizing water-soluble, monoethylenically unsaturated, surface-active monomers and monoethylenically unsaturated hydrophilic monomers in the presence of surfactants, and the use of such copolymers for polymer flooding.
- Our prior applications EP 10192323.3, EP 10192334.0 and EP 10192316.7 disclose the use of the hydrophobically associating copolymers disclosed in WO 2010/133527 A2 in specific processes for polymer flooding.
- However, none of the latter cited applications discloses the use of such hydrophobically associating copolymers for blocking of underground mineral oil-bearing formations.
- It was an object of the invention to provide an improved process for blocking of highly permeable regions of mineral oil-bearing formations.
- Accordingly, a process has been found for producing mineral oil from underground mineral oil deposits, which comprises at least the following process steps:
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- (1) blocking permeable regions of the underground mineral oil deposit by injecting an aqueous formulation into the formation through at least one well, said aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer, and
- (2) injecting an aqueous flooding medium into at least one injection well and withdrawing mineral oil through the at least one production well, and wherein
- the water-soluble, hydrophobically associating copolymer comprises
- (a) 0.1 to 15% by weight of at least one monoethylenically unsaturated, hydrophobically associating monomer (a) selected from the group of
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H2C═C(R1)—R2—O—(—CH2—CH(R3)—O—)k—(—CH2—CH(R4)—O—)l—R5 (I), -
H2C═C(R1)—O—(—CH2—CH(R3)—O—)k—R6 (II), -
H2C═C(R1)—(C═O)—O—(—CH2—CH(R3)—O—)k—R6 (III), -
-
- where the —(—CH2—CH(R3)—O—)k and —(—CH2—CH(R4)—O—)l units are arranged in block structure in the sequence shown in formula (I) and the radicals and indices are each defined as follows:
- k: a number from 10 to 150,
- l: a number from 5 to 25,
- R1: H or methyl,
- R2: a single bond or a divalent linking group selected from the group of —(CnH2n)—[R2a], —O—(Cn′H2n′)—[R2b] and —C(O)—O—(Cn″H2n″)—[R2c], where n, n′ and n″ are each natural numbers from 1 to 6,
- R3: each independently H, methyl or ethyl, with the proviso that at least 50 mol % of the R3 radicals are H,
- R4: each independently a hydrocarbyl radical having at least 2 carbon atoms or an ether group of the general formula —CH2—O—R4′, where R4′ is a hydrocarbyl radical having at least 2 carbon atoms,
- R5: H or a hydrocarbyl radical having 1 to 30 carbon atoms,
- R6: an aliphatic and/or aromatic, straight-chain or branched hydrocarbyl radical having 8 to 40 carbon atoms,
- and also
- (b) 85 to 99.9% by weight of at least two monoethylenically unsaturated monomers (b) different than (a), where the monomers (b) comprise
- (b1) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer (b1), selected from the group of (meth)acrylamide, N-methyl(meth)acrylamide, N,N′-dimethyl(meth)acrylamide or N-methylol(meth)acrylamide, and
- (b2) at least one monomer (b2a) and/or (b2b), where the monomers (b2a) and (b2b) are defined as follows:
- (b2a) anionic, monoethylenically unsaturated, hydrophilic monomers which have at least one acidic group selected from the group of —COOH, —SO3H and —PO3H2 and salts thereof,
- (b2b) (meth)acrylic esters of the general formula H2C═C(R15)—COOR16 where R15 is H or methyl and R16 is a straight-chain or branched alkyl radical having 1 to 8 carbon atoms, with the proviso that the amount of the monomers (b2b), if present, does not exceed 20% by weight,
- where the proportions are each based on the total amount of all monomers in the copolymer,
- the copolymer has a weight-average molecular weight Mw of 0.5*106 g/mol to 30*106 g/mol,
- the amount of the copolymer in the aqueous formulation is 0.1 to 3% by weight, and
- the deposit temperature is 20° C. to 120° C.
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FIG. 1 illustrates the results of the viscosity measurements. - With regard to the invention, the following should be stated specifically:
- The process according to the invention comprises at least two process steps, (1) and (2).
- In process step (1), permeable regions of the underground mineral oil deposit are blocked by injecting an aqueous formulation through at least one well sunk into the formation, said aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer. The term “blocking” means here that the permeable regions are completely or at least partially blocked. “Partially blocked” is intended to mean that the flow resistance of the permeable regions for aqueous media increases due to the treatment with the aqueous formulation of the copolymer. This can occur, for example, as a result of the copolymer forming a gel in the permeable regions of the formation and blocking them, or it can occur as a result of the copolymer forming a coating on the inner surface of cavities in the formation and this constriction of the flow paths increasing the flow resistance in the permeable regions.
- In process step (2), mineral oil is actually produced by injecting an aqueous flooding medium into at least one injection well and withdrawing mineral oil through at least one production well. The injected aqueous flooding medium maintains the pressure and forces the mineral oil from the injection wells in the direction of the production wells.
- The result of the performance of process step (1) here, i.e. the blocking of permeable zones, is that the flooding medium injected in process step (2) is forced also to flow through less permeable, as yet unexploited regions of the underground formation. As a result, the mineral oil yield is increased and water production is reduced.
- Process steps (1) and (2) can also be performed more than once in the context of the process according to the invention, and the process according to the invention may of course comprise further process steps.
- The mineral oil deposits to which the process according to the invention is applied may be deposits for all kinds of oil, for example those for light or heavy oil.
- In addition to mineral oil and possibly natural gas, the deposits generally comprise deposit water with a greater or lesser salt content. Typical salts in deposit waters comprise especially alkali metal salts and alkaline earth metal salts. Examples of typical cations comprise Na+, K+, Mg2+ and Ca2+, and examples of typical anions comprise chloride, bromide, hydrogencarbonate, sulfate or borate. The process according to the invention is especially suitable for deposits with a total amount of all salts in the deposit water of 20 000 ppm to 350 000 ppm (parts by weight), preferably 100 000 ppm to 250 000 ppm. The amount of alkaline earth metal ions in the deposit water may especially be 1000 to 53 000 ppm.
- The mineral oil deposits have inhomogeneous permeability. This is understood to mean that the permeability is not the same in all regions of the deposit, and that the deposit instead has regions of higher and lower permeability. Regions of higher permeability may be caused, for example, by the fact that the deposits have larger pores in this region, or else by the fact that the deposits have fractures, cracks, fissures or the like. In the course of continued injection of water into the formation to maintain the pressure, called water flooding, the water injected, due to the low flow resistance, flows preferentially through the regions of high permeability.
- The deposit may also have different rock layers of different permeability arranged one on top of another. For example, a deposit may comprise a comparatively permeable layer essentially comprising water, and a lower, less permeable layer comprising mineral oil.
- The deposit temperatures (TL) are in the range from 20° C. to 120° C., especially 30° C. to 120° C., preferably 35° C. to 110° C., more preferably 40° C. to 100° C., even more preferably 45° C. to 90° C. and, for example, 50° C. to 75° C. It will be clear to the person skilled in the art that a mineral oil deposit may also have a certain temperature distribution. The deposit temperature mentioned relates to the region of the deposit between the injection and production wells, i.e. the region covered by process steps (1) and (2). The temperature distribution can generally be undertaken from temperature measurements at particular sites in the formation in combination with simulation calculations, the simulation calculations taking account of factors including amounts of heat introduced into the formation and the amounts of heat removed from the formation.
- To execute process step (1) of the process according to the invention, at least one well is sunk into the mineral oil deposit, through which the aqueous copolymer formulation can be injected to block permeable regions. This may be a well which has been sunk specially for process step (1). It is preferably an injection well and/or a production well which can also be used for process step (2) and/or has already been used in preceding water flooding.
- To execute process step (2), at least one production well and at least one injection well are sunk into the mineral oil deposit. In general, a deposit is provided with several injection wells and with several production wells. Aqueous formulations can be injected into the mineral oil deposit through the at least one injection well, and the production wells serve to withdraw mineral oil from the mineral oil deposit. The term “mineral oil” in this context does not of course mean only single-phase oil, but instead the term also comprises the customary crude oil-water emulsions wherein the water may either be deposit water or injected water which has penetrated as far as the production well.
- The wells which can be used for process step (1) may preferably be the injection and/or production wells which are also used for process step (2).
- In process step (1), an aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer is used. In addition to the at least one copolymer, the formulation may optionally comprise further components.
- The term “hydrophobically associating copolymers” is known in principle to those skilled in the art.
- They comprise water-soluble copolymers which, as well as hydrophilic molecular components, have hydrophobic groups. In aqueous solution, the hydrophobic groups can associate with themselves or with other substances having hydrophobic groups due to intermolecular forces. This gives rise to a polymeric network joined by intermolecular forces, which thickens the aqueous medium.
- In the ideal case, the copolymers used in accordance with the invention should be miscible with water in any ratio. According to the invention, however, it is sufficient when the copolymers are water-soluble at least at the desired use concentration and at the desired pH. In general, the solubility in water at room temperature under the use conditions should be at least 35 WI.
- According to the invention, the water-soluble, hydrophobically associating copolymer used comprises 0.1 to 15% by weight of at least one monoethylenically unsaturated, hydrophobically associating monomer (a) and 85 to 99.9% by weight of at least two monoethylenically unsaturated, hydrophilic monomers (b) different than (a). In addition, it is optionally possible for further, ethylenically unsaturated, preferably monoethylenically unsaturated, monomers (c) different than the monomers (a) and (b) to be present in an amount of up to 14.9% by weight. The amounts mentioned are each based on the sum of all monomers in the copolymer. Preference is given to using exclusively monoethylenically unsaturated monomers.
- The water-soluble, hydrophobically associating copolymer used comprises at least one monoethylenically unsaturated monomer (a) which imparts hydrophobically associating properties to the copolymer and shall therefore be referred to hereinafter as “hydrophobically associating monomer”. According to the invention, the monomers (a) are selected from the group of
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H2C═C(R1)—R2—O—(—CH2—CH(R3)—O—)k—(—CH2—CH(R4)—O—)l—R5 (I), -
H2C═C(R1)—O—(—CH2—CH(R3)—O—)k—R6 (II), -
H2C═C(R1)—(C═O)—O—(—CH2—CH(R3)—O—)k—R6 (III). - In the monomers (a) of the formula (I), an ethylenic group H2C═C(R1)— is bonded via a divalent linking group —R2—O— to a polyoxyalkylene radical with block structure —(—CH2—CH(R3)—O—)k—(—CH2—CH(R4)—O—)r—R5, where the two blocks —(—CH2—CH(R3)—O—)k and —CH2—CH(R4)—O—)l are arranged in the sequence shown in formula (I). The polyoxyalkylene radical has either a terminal OH group or a terminal ether group —OR5.
- In the abovementioned formula, R1 is H or a methyl group.
- R2 is a single bond or a divalent linking group selected from the group of —(CnH2n)—[R2a group], —O—(Cn′H2n′)—[R2b group]- and —C(O)—O—(Cn″H2″)—[R2c group]. In the formulae mentioned, n, n′ and n″ are each a natural number from 1 to 6. In other words, the linking group comprises straight-chain or branched aliphatic hydrocarbyl groups having 1 to 6 hydrocarbon atoms, which are joined to the ethylenic group H2C═C(R1)— directly, via an ether group —O— or via an ester group —C(O)—O—. The —(CnH2n)—, —(Cn′H2n′)— and —(Cn″H2n″)— groups are preferably linear aliphatic hydrocarbyl groups.
- The R2a group is preferably a group selected from —CH2—, —CH2—CH2— and —CH2—CH2—CH2—, more preferably a methylene group —CH2—.
- The R2b group is preferably a group selected from —O—CH2—CH2—, —O—CH2—CH2—CH2— and —O—CH2—CH2—CH2—CH2—, more preferably —O—CH2—CH2—CH2—CH2—.
- The R2c group is preferably a group selected from —C(O)—O—CH2—CH2—, —C(O)O—CH(CH3)—CH2—, —C(O)O—CH2—CH(CH3)—, —C(O)O—CH2—CH2—CH2—CH2— and —C(O)O—CH2—CH2—CH2—CH2—CH2—CH2—, more preferably —C(O)—O—CH2—CH2— and —C(O)O—CH2—CH2—CH2—CH2—, and most preferably —C(O)—O—CH2—CH2—.
- The R2 group is more preferably an R2a or R2b group, more preferably an R2b group.
- In addition, R2 is more preferably a group selected from —CH2— and —O—CH2—CH2—CH2—CH2—, most preferably —O—CH2—CH2—CH2—CH2—.
- The monomers (I) also have a polyoxyalkylene radical which consists of the units —(—CH2—CH(R3)—O—)k and —(—CH2—CH(R4)—O—)l where the units are arranged in block structure in the sequence shown in formula (I). The transition between the two blocks may be abrupt or else continuous.
- In the —(—CH2—CH(R3)—O—)k block, the R3 radicals are each independently H, methyl or ethyl, preferably H or methyl, with the proviso that at least 50 mol % of the R3 radicals are H. Preferably at least 75 mol % of the R3 radicals are H, more preferably at least 90 mol %, and they are most preferably exclusively H. The block mentioned is thus a polyoxyethylene block which may optionally also have certain proportions of propylene oxide and/or butylene oxide units, preferably a pure polyoxyethylene block.
- The number of alkylene oxide units k is a number from 10 to 150, preferably 12 to 100, more preferably 15 to 80, even more preferably 20 to 30 and, for example, approx. 22 to 25. It is clear to the person skilled in the art in the field of the polyalkylene oxides that the numbers mentioned are averages of distributions.
- In the second, terminal —(—CH2—CH(R4)—O—)l— block, the R4 radicals are each independently hydrocarbyl radicals of at least 2 carbon atoms, preferably at least 3, more preferably 3 to 10 and most preferably 3 to 4 carbon atoms. This may be an aliphatic and/or aromatic, linear or branched carbon radical. It is preferably an aliphatic radical.
- Examples of suitable R4 radicals comprise ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl or n-decyl, and phenyl. Examples of preferred radicals comprise n-propyl, n-butyl, n-pentyl, particular preference being given to an n-propyl radical.
- The R4 radicals may also be ether groups of the general formula —CH2—O—R4′ where R4′ is an aliphatic and/or aromatic, linear or branched hydrocarbyl radical having at least 2 carbon atoms, preferably at least 3 and more preferably 3 to 10 carbon atoms. Examples of R3′ radicals comprise n-propyl, n-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or phenyl.
- The —(—CH2—CH(R4)—O—)l— block is thus a block which consists of alkylene oxide units having at least 4 carbon atoms, preferably at least 5 carbon atoms, and/or glycidyl ethers having an ether group of at least 2, preferably at least 3, carbon atoms. Preferred R3 radicals are the hydrocarbyl radicals mentioned; the units of the second terminal block are more preferably alkylene oxide units comprising at least 5 carbon atoms, such as pentene oxide units or units of higher alkylene oxides.
- The number of alkylene oxide units I is a number from 5 to 25, preferably 6 to 20, more preferably 8 to 18, even more preferably 10 to 15 and, for example, approx. 12.
- The R5 radical is H or a preferably aliphatic hydrocarbyl radical having 1 to 30 carbon atoms, preferably 1 to 10 and more preferably 1 to 5 carbon atoms. R5 is preferably H, methyl or ethyl, more preferably H or methyl and most preferably H.
- In the monomers of the formula (I), a terminal monoethylenic group is joined to a polyoxyalkylene group with block structure, specifically firstly to a hydrophilic block having polyethylene oxide units, which is in turn joined to a second terminal hydrophobic block formed at least from butene oxide units, preferably at least pentene oxide units, or units of higher alkylene oxides, for example dodecene oxide. The second block has a terminal —OR5-group, especially an OH-group. The terminal —(—CH2—CH(R4)—O—)l block with the R4 radicals is responsible for the hydrophobic association of the copolymers prepared using the monomers (a). Etherification of the OH end group is an option which may be selected by the person skilled in the art according to the desired properties of the copolymer. A terminal hydrocarbyl group is, however, not required for the hydrophobic association, and the hydrophobic association also works with a terminal OH group.
- It is clear to the person skilled in the art in the field of polyalkylene oxide block copolymers that the transition between the two blocks, according to the method of preparation, may be abrupt or else continuous. In the case of a continuous transition, there is a transition zone between the two blocks, which comprises monomers of both blocks. When the block boundary is fixed at the middle of the transition zone, the first block —(—CH2—CH(R3)—O—)k may accordingly also have small amounts of —CH2—CH(R4)—O— units and the second block —(—CH2—CH(R4)—O—)l— small amounts of —CH2—CH(R3)—O— units, though these units are not distributed randomly over the block but arranged in the transition zone mentioned.
- The hydrophobically associating monomers (a) of the formula (I) can be prepared by methods known in principle to those skilled in the art.
- To prepare the monomers (a), a preferred preparation process proceeds from suitable monoethylenically unsaturated alcohols (IV) which are subsequently alkoxylated in a two-stage process such that the block structure mentioned is obtained. This gives monomers (a) of the formula (I) where R5═H. These can optionally be etherified in a further process step.
- The type of ethylenically unsaturated alcohols (IV) to be used is guided here especially by the R2 group.
- When R2 is a single bond, the starting materials are alcohols (IV) of the general formula H2C═C(R1)—O—(—CH2—CH(R7)—O—)d—H (IVa) where R1 is as defined above, R7 is H and/or CH3, preferably H, and d is a number from 1 to 5, preferably 1 or 2. Examples of such alcohols comprise diethylene glycol vinyl ether H2C═CH—O—CH2—CH2—O—CH2—CH2—OH or dipropylene glycol vinyl ether H2C═CH—O—CH2—CH(CH3)—O—CH2—CH(CH3)—OH, preferably diethylene glycol vinyl ether.
- To prepare monomers (a) in which R2 is not a single bond, it is possible to use alcohols of the general formula H2C═C(R1)—R2—OH (IVb) or alcohols which already have alkoxy groups and are of the formula H2C═C(R1)—R2—O—(—CH2—CH(R7)—O—)d—H (IVc), where R7 and d are each as defined above, and R2 in each case is selected from the group of R2a, R2b and R2c.
- The preparation of the monomers with a linking R2a group preferably proceeds from alcohols of the formula H2C═C(R1)—(CnH2n)—OH, especially H2C═CH—(CnH2n)—OH, or alcohols of the formula H2C═C(R1)—O—(—CH2—CH(R7)—O—)d—H. Examples of preferred alcohols comprise allyl alcohol H2C═CH—CH2—OH or isoprenol H2C═C(CH3)—CH2—CH2—OH.
- The preparation of the monomers with a linking R2b group proceeds from vinyl ethers of the formula H2C═C(R1)—O—(Cn′H2n′)—OH, preferably H2C═CH—O—(Cn′H2n′)—OH. It is more preferably possible to use w-hydroxybutyl vinyl ether H2C═CH—O—CH2—CH2—CH2—CH2—OH.
- The preparation of the monomers with a linking R2 group proceeds from hydroxyalkyl (meth)acrylates of the general formula H2C═C(R1)—C(O)—O—(Cn″H2n″)—OH, preferably H2C═C(R1)—C(O)—O—(Cn″H2n″)—OH. Examples of preferred hydroxyalkyl (meth)acrylates comprise hydroxyethyl (meth)acrylate H2C═C(R1)—C(O)—O—CH2—CH2—OH and hydroxybutyl (meth)acrylate H2C═C(R1)—C(O)—O—CH2—CH2—CH2—CH2—OH.
- The starting compounds mentioned are alkoxylated, specifically in a two-stage process, first with ethylene oxide, optionally in a mixture with propylene oxide and/or butylene oxide, and in a second step with alkylene oxides of the general formula (Xa) or (Xb)
- where R4 in (Xa) and R4′ in (Xb) are each as defined at the outset.
- The performance of an alkoxylation including the preparation of block copolymers from different alkylene oxides is known in principle to those skilled in the art. It is likewise known to those skilled in the art that the reaction conditions, especially the selection of the catalyst, can influence the molecular weight distribution of the alkoxylates and the orientation of alkylene oxide units in a polyether chain.
- The alkoxylates can be prepared, for example, by base-catalyzed alkoxylation. For this purpose, the alcohol used as the starting material can be admixed in a pressure reactor with alkali metal hydroxides, preferably potassium hydroxide, or with alkali metal alkoxides, for example sodium methoxide. By means of reduced pressure (e.g. <100 mbar) and/or increasing the temperature (30 to 150° C.), water still present in the mixture can be removed. Thereafter, the alcohol is present as the corresponding alkoxide. This is followed by inertization with inert gas (e.g. nitrogen) and, in a first step, stepwise addition of ethylene oxide, optionally in a mixture with propylene oxide and/or butylene oxide, at temperatures of 60 to 180° C., preferably 130 to 150° C. The addition is typically effected within 2 to 5 h, though the invention should not be restricted thereto. After the addition has ended, the reaction mixture is appropriately allowed to continue to react, for example for ½ h to 1 h. In a second step, alkylene oxides of the general formula (Xb) are subsequently metered in stepwise. The reaction temperature in the second stage can be maintained or else altered. A reaction temperature lower by approx. 10 to 25° C. than in the first stage has been found to be useful.
- The alkoxylation can also be undertaken by means of techniques which lead to narrower molecular weight distributions than the base-catalyzed synthesis. For this purpose, the catalysts used may, for example, be double hydroxide clays as described in DE 43 25 237 A1. The alkoxylation can more preferably be effected using double metal cyanide catalysts (DMC catalysts). Suitable DMC catalysts are disclosed, for example, in DE 102 43 361A1, especially paragraphs [0029] to [0041] and the literature cited therein. For example, it is possible to use catalysts of the Zn—Co type. To perform the reaction, the alcohol used as the starting material can be admixed with the catalyst, and the mixture can be dewatered as described above and reacted with the alkylene oxides as described. Typically, not more than 250 ppm of catalyst based on the mixture are used, and the catalyst can remain in the product due to this small amount.
- The alkoxylation can additionally also be undertaken under acid catalysis. The acids may be Brønsted or Lewis acids. To perform the reaction, the alcohol used as the starting material can be admixed with the catalyst, and the mixture can be dewatered as described above and reacted with the alkylene oxides as described. At the end of the reaction, the acidic catalyst can be neutralized by addition of a base, for example KOH or NaOH, and filtered off if required.
- It is clear to the person skilled in the art in the field of the polyalkylene oxides that the orientation of the hydrocarbyl radicals R4 and optionally R3 may depend on the conditions of the alkoxylation, for example on the catalyst selected for the alkoxylation. The alkylene oxide groups can thus be incorporated into the monomer either in the —(—CH2—CH(R4)—O—) orientation or else in the inverse —(—CH(R4)—CH2—O—)— orientation. The description in formula (I) should therefore not be considered to be restricted to a particular orientation of the R3 or R4 groups.
- When the terminal OH group of the monomers (a) of the formula (I) (i.e. R5═H) is to be etherified, this can be accomplished with customary alkylating agents known in principle to those skilled in the art, for example alkyl sulfates. For etherification, it is especially possible to use dimethyl sulfate or diethyl sulfate.
- The preferred preparation process described for the monomers (I) has the advantage that the formation of possibly crosslinking by-products is substantially avoided. Accordingly, it is possible to obtain copolymers with a particularly low gel content.
- In the monomers of the formulae (II) and (III), R1, R3 and k are each defined as already outlined.
- R6 is an aliphatic and/or aromatic, straight-chain or branched hydrocarbyl radical having 8 to 40 carbon atoms, preferably 12 to 32 carbon atoms. For example, it may comprise n-alkyl groups such as n-octyl, n-decyl or n-dodecyl groups, phenyl groups, and especially substituted phenyl groups. Substituents on the phenyl groups may be alkyl groups, for example C1-C6-alkyl groups, preferably styryl groups. Particular preference is given to a tristyrylphenyl group.
- The hydrophobically associating monomers of the formulae (II) and (III) and the preparation thereof are known in principle to those skilled in the art, for example from EP 705 854 A1.
- The amount of the monoethylenically unsaturated, hydrophobically associating monomers (a) is 0.1 to 15% by weight, based on the total amount of all monomers in the copolymer, especially 0.1 to 10% by weight, preferably 0.2 to 5% by weight and more preferably 0.5 to 5% by weight and, for example, 0.5 to 2% by weight.
- Particular preference is given to using monomers (a) of the general formula (I) to prepare the inventive copolymers.
- Over and above the monomers (a), the hydrophobically associating copolymer used in accordance with the invention comprises at least two monoethylenically unsaturated monomers (b) different than (a). referred to hereinafter as (b1) and (b2).
- The monomers (b1) are uncharged, hydrophilic monomers.
- The monomers (b2) are anionic, hydrophilic monomers (b2a) and/or (meth)acrylic esters (b2b). The (meth)acrylic esters themselves are, according to the nature of the ester group, generally not hydrophilic, but can be hydrolyzed under formation conditions to form hydrophilic groups.
- More preferably, the hydrophilic monomers (b1) and (b2a) used are miscible with water in any ratio, but it is sufficient for execution of the invention that the inventive, hydrophobically associating copolymer possesses the water solubility mentioned at the outset. In general, the solubility of the monomers (b1) and (b2a) in water at room temperature should be at least 50 g/l, preferably at least 150 g/l and more preferably at least 250 g/l.
- According to the invention, the copolymer comprises at least one uncharged, monoethylenically unsaturated, hydrophilic monomer (b1) selected from the group of (meth)acrylamide, N-methyl(meth)acrylamide, N,N′-dimethyl(meth)acrylamide or N-methylol(meth)acrylamide. Preference is given to (meth)acrylamide, especially acrylamide. When mixtures of different monomers (b1) are used, at least 50 mol % of the monomers (b1) should be (meth)acrylamide, preferably acrylamide.
- According to the invention, the copolymer used further comprises at least monomer (b2a) and/or (b2b).
- Monomer (b2a) comprises hydrophilic, monoethylenically unsaturated anionic monomers which have at least one acidic group selected from the group of —COOH, —SO3H and —PO3H2 and salts thereof. Preference is given to monomers comprising COOH groups and/or —SO3H groups, particular preference to monomers comprising —SO3H groups. The monomers may of course also be the salts of the acidic monomers. Suitable counterions comprise especially alkali metal ions such as Li+, Na+ or K+, and ammonium ions such as NH4 + or ammonium ions with organic radicals.
- Examples of monomers comprising COOH groups comprise acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid. Preference is given to acrylic acid.
- Examples of monomers comprising sulfo groups comprise vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid or 2-acrylamido-2,4,4-trimethylpentanesulfonic acid. Preference is given to vinylsulfonic acid, allylsulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid, and particular preference to 2-acrylamido-2-methylpropanesulfonic acid.
- Examples of monomers comprising phospho groups comprise vinylphosphonic acid, allylphosphonic acid, N-(meth)acrylamidoalkylphosphonic acids or (meth)acryloyloxyalkyl-phosphonic acids, preference being given to vinylphosphonic acid.
- For the sake of completeness, it should be mentioned that the monomers (b1) can be hydrolyzed at least partly to (meth)acrylic acid under some circumstances in the course of preparation and use of the copolymers. The hydrolysis can of course also be undertaken deliberately by the person skilled in the art. The copolymers used in accordance with the invention may accordingly comprise (meth)acrylic acid units, even if (meth)acrylic acid itself has not been used for the synthesis. The tendency to hydrolysis of the monomers (b1) decreases with increasing content of sulfo groups. Accordingly, the presence of sulfo groups in the copolymer used in accordance with the invention is advisable. The monomers (b2b) are (meth)acrylic esters of the general formula H2C═C(R15)—COOR16. For example, R16 may be methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, i-butyl, 1-pentyl, 1-hexyl, 1-heptyl or 1-octyl radicals.
- R15 here is H or methyl, preferably H. R16 is a straight-chain or preferably branched alkyl radical having 1 to 8 carbon atoms.
- R16 is preferably a secondary alkyl radical —CH(R17)(R17′), where R17 and R17′ are straight-chain or branched alkyl radicals, with the proviso that the total number of carbon atoms in the R17 and R17′ radicals is 2 to 7. Examples of such secondary alkyl radicals comprise 2-propyl, 2-butyl or 2-pentyl radicals.
- Additionally preferably, R16 is a tertiary alkyl radical —C(R18)(R18′)(R18″), where R18, R18′, R18″ are straight-chain or branched alkyl radicals, with the proviso that the total number of carbon atoms in the R18, R18′ and R18″ radicals is 3 to 7. A particularly preferred tertiary alkyl radical is a t-butyl radical —C(CH3)3.
- The ester groups of the (meth)acrylic esters (b2b) can, after being incorporated into the copolymer, be hydrolyzed to —COOH groups or salts thereof, especially under formation conditions, i.e. especially elevated temperature. This results in in situ formation of polymers comprising the units (b1) and (b2a). Esters having secondary and especially tertiary alkyl radicals are hydrolyzed more quickly than esters of primary alkyl radicals and are therefore particularly preferred.
- The copolymers used in accordance with the invention may additionally optionally comprise at least one monoethylenically unsaturated, cationic monomer (b3) having ammonium ions.
- Suitable cationic monomers (b3) comprise especially monomers having ammonium groups, especially ammonium derivatives of N-(w-aminoalkyl)(meth)acrylamides or w-aminoalkyl-(meth)acrylic esters, and also diallyldimethylammonium salts.
- More particularly, monomers (b3) having ammonium groups may be compounds of the general formulae H2C═C(R8)—CO—NR9—R10—NR11 3 +X− (Va) and/or H2C═C(R8)—COO—R10—NR11 3 +X− (Vb). In these formulae, R8 is H or methyl, R9 is H or a C1-C4-alkyl group, preferably H or methyl, and R10 is a preferably linear C1-C4-alkylene group, for example a 1,2-ethylene group —CH2—CH2— or a 1,3-propylene group —CH2—CH2—CH2—.
- The R11 radicals are each independently C1-C4-alkyl radicals, preferably methyl, or a group of the general formula —R12—SO3H where R12 is a preferably linear C1-C4-alkylene group or a phenyl group, with the proviso that generally not more than one of the R11 substituents is a substituent having sulfo groups. More preferably, the three R11 substituents are methyl groups, i.e. the monomer has a —N(CH3)3 + group. X− in the above formula is a monovalent anion, for example Cl−. X− may of course also be a corresponding fraction of a polyvalent anion, though this is not preferred. Examples of preferred monomers (b3) of the general formula (Va) or (Vb) comprise salts of 3-trimethylammoniopropyl(meth)acrylamides or 2-trimethylammonioethyl (meth)acrylates, for example the corresponding chlorides such as 3-trimethylammoniopropyl-acrylamide chloride (DIMAPAQUAT) and 2-trimethylammoniomethyl methacrylate chloride (MADAME-QUAT).
- The copolymers used in accordance with the invention may additionally also comprise further monoethylenically unsaturated hydrophilic monomers (b4) different than the hydrophilic monomers (b1), (b2) and (b3). Examples of such monomers comprise monomers comprising hydroxyl groups and/or ether groups, for example hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, allyl alcohol, hydroxyvinyl ethyl ether, hydroxyvinyl propyl ether, hydroxyvinyl butyl ether, or compounds of the formula H2C═C(R1)—COO—(—CH2—CH(R13)—O—)b—R14 (Vla) or H2C═C(R1)—O—(—CH2—CH(R13)—O—)b—R14 (Vlb), where R1 is as defined above and b is a number from 2 to 200, preferably 2 to 100. The R13 radicals are each independently H, methyl or ethyl, preferably H or methyl, with the proviso that at least 50 mol % of the R13 radicals are H. Preferably at least 75 mol % of the R13 radicals are H, more preferably at least 90 mol %, and they are most preferably exclusively H. The R14 radical is H, methyl or ethyl, preferably H or methyl. Further examples of monomers (b4) comprise N-vinyl derivatives, for example N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone or N-vinylcaprolactam, and vinyl esters, for example vinyl formate or vinyl acetate. N-Vinyl derivatives can be hydrolyzed after polymerization to give vinylamine units, and vinyl esters to give vinyl alcohol units.
- Copolymers used with preference comprise monomers (b1) and (b2a), but no monomers (b2b).
- Further copolymers used with preference comprise monomers (b1) and (b2b), but no monomers (b2a). As explained above, however, it is also possible in this case for the ester groups of the monomers (b2b) to be hydrolyzed to —COOH groups, especially under formation conditions, and so such copolymers may also have —COOH groups some time after employment.
- The amount of all monomers (b) in the inventive copolymer is, in accordance with the invention, 85 to 99.9% by weight, based on the total amount of all monomers in the copolymer, preferably 90 to 99.8% by weight.
- The amount of the uncharged, hydrophilic monomers (b1) here is generally 30 to 95% by weight, preferably 30 to 85% by weight and more preferably 30 to 70% by weight, based on the total amount of all monomers used.
- When the copolymer comprises only uncharged monomers (b1) and anionic monomers (b2a), it has been found to be useful to use the uncharged monomers (b1) in an amount of 30 to 95% by weight and the anionic monomers (b2a) in an amount of 4.9 to 69.9% by weight, each amount being based on the total amount of all monomers used. In this embodiment, the monomers (b1) are preferably used in an amount of 30 to 80% by weight and the anionic monomers (b2a) in an amount of 19.9 to 69.9% by weight, and the monomers (b1) are more preferably used in an amount of 40 to 70% by weight and the anionic monomers (b2a) in an amount of 29.9 to 59.9% by weight.
- When the copolymer comprises uncharged monomers (b1), anionic monomers (b2a) and cationic monomers (b3), it has been found to be useful to use the uncharged monomers (b1) in an amount of 30 to 95% by weight, and the anionic (b2a) and cationic (b3) monomers together in an amount of 4.9 to 69.9% by weight, with the proviso that the molar (b2a)/(b3) ratio is 0.7 to 1.3. The molar (b2a)/(b3) ratio is preferably 0.8 to 1.2 and, for example, 0.9 to 1.1. This measure makes it possible to obtain copolymers which are particularly insensitive to salt burden. In this embodiment, the monomers (b1) are preferably used in an amount of 30 to 80% by weight, and the anionic and cationic monomers (b2a)+(b3) together in an amount of 19.9 to 69.9% by weight, and the monomers (b1) are more preferably used in an amount of 40 to 70% by weight and the anionic and cationic monomers (b2a)+(b3) together in an amount of 29.9 to 59.9% by weight, where the molar ratio already mentioned should be observed in each case. The amount of the monomers (b2b) is judged by the person skilled in the art such that the water solubility of the copolymer is not impaired by the use of the monomers (b2b). The amount of the monomers (b2b) should therefore generally, if present, not exceed 20% by weight, based on the total amount of all monomers. The amount should preferably not exceed 10% by weight. It may, for example, be 0.5 to 5% by weight.
- In addition to the hydrophilic monomers (a) and (b), the inventive copolymers may optionally comprise ethylenically unsaturated monomers different than the monomers (a) and (b), preferably monoethylenically unsaturated monomers (c). Of course, it is also possible to use mixtures of a plurality of different monomers (c).
- Such monomers can be used for fine control of the properties of the copolymer used in accordance with the invention. If present at all, the amount of such optionally present monomers (c) may be up to 14.9% by weight, preferably up to 9.9% by weight, more preferably up to 4.9% by weight, based in each case on the total amount of all monomers. Most preferably, no monomers (c) are present.
- The monomers (c) may, for example, be monoethylenically unsaturated monomers which have more hydrophobic character than the hydrophilic monomers (b1) and (b2a) and which are accordingly water-soluble only to a minor degree. In general, the solubility of the monomers (c) in water at room temperature is less than 50 g/l, especially less than 30 g/l. Examples of such monomers comprise N-alkyl- and N,N″-dialkyl(meth)acrylamides, where the number of carbon atoms in the alkyl radicals together is at least 3, preferably at least 4. Examples of such monomers comprise N-butyl(meth)acrylamide, N-cyclohexyl(meth)acrylamide or N-benzyl(meth)acrylamide.
- The copolymers used in accordance with the invention can be prepared by methods known in principle to those skilled in the art, by free-radical polymerization of the monomers (a), (b) and optionally (c), for example by solution or gel polymerization in the aqueous phase.
- For polymerization, the monomers (a), (b), optionally (c), initiators and optionally further assistants for polymerization are used in an aqueous medium.
- In a preferred embodiment, the preparation is undertaken by means of gel polymerization in the aqueous phase. For gel polymerization, a mixture of the monomers (a), (b) and optionally (c), initiators and optionally further assistants with water or an aqueous solvent mixture is first provided. Suitable aqueous solvent mixtures comprise water and water-miscible organic solvents, where the proportion of water is generally at least 50% by weight, preferably at least 80% by weight and more preferably at least 90% by weight. Organic solvents in this context include especially water-miscible alcohols such as methanol, ethanol or propanol. Acidic monomers can be fully or partly neutralized before the polymerization. The concentration of all components except the solvents in the course of the polymerization is typically approx. 20 to 60% by weight, preferably approx. 30 to 50% by weight. The polymerization should especially be performed at a pH in the range from 5.0 to 7.5 and preferably at a pH of 6.0.
- In a preferred embodiment of the invention, the copolymers used are prepared in the presence of at least one nonpolymerizable, surface-active compound (T).
- The nonpolymerizable, surface-active compound (T) is preferably at least one nonionic surfactant, but anionic and cationic surfactants are also suitable to the extent that they do not take part in the polymerization reaction. They may especially be surfactants, preferably nonionic surfactants, of the general formula R13—Y′ where R13 is a hydrocarbyl radical having 8 to 32, preferably 10 to 20 and more preferably 12 to 18 carbon atoms, and Y′ is a hydrophilic group, preferably a nonionic hydrophilic group, especially a polyalkoxy group.
- The nonionic surfactant is preferably an ethoxylated long-chain aliphatic alcohol which may optionally comprise aromatic components.
- Examples include: C12C14-fatty alcohol ethoxylates, C16C18-fatty alcohol ethoxylates, C13-oxo alcohol ethoxylates, C10-oxo alcohol ethoxylates, C13C15-oxo alcohol ethoxylates, C10-Guerbet alcohol ethoxylates and alkylphenol ethoxylates. Useful compounds have especially been found to be those having 5 to 20 ethyleneoxy units, preferably 8 to 18 ethyleneoxy units. It is optionally also possible for small amounts of higher alkyleneoxy units to be present, especially propyleneoxy and/or butyleneoxy units, though the amount in the form of ethyleneoxy units should generally be at least 80 mol % based on all alkyleneoxy units.
- Especially suitable are surfactants selected from the group of the ethoxylated alkylphenols, the ethoxylated, saturated iso-C13-alcohols and/or the ethoxylated C10-Guerbet alcohols, where in each case 5 to 20 ethyleneoxy units, preferably 8 to 18 ethyleneoxy units, are present in alkoxy radicals.
- Surprisingly, the addition of nonpolymerizable, interface-active compounds (T) during the polymerization leads to a distinct improvement in performance properties of the copolymer in polymer flooding. More particularly, the thickening action is increased and the gel content of the copolymer is also reduced. This effect can probably be explained as follows, without any intention that the invention thus be tied to this explanation. In the case of polymerization without the presence of a surfactant, the hydrophobically associating comonomers (a) form micelles in the aqueous reaction medium. In the polymerization, this leads to blockwise incorporation of the hydrophobically associating regions into the polymer. If, in accordance with the invention, an additional surface-active compound is present in the preparation of the copolymers, mixed micelles form. These mixed micelles comprise polymerizable and nonpolymerizable components. As a result, the hydrophobically associating monomers are then incorporated in relatively short blocks. At the same time, the number of these relatively short blocks is greater per polymer chain. Thus, the structure of the copolymers prepared in the presence of a surfactant differs from those without the presence of a surfactant.
- The nonpolymerizable, interface-active compounds (T) can generally be used in an amount of 0.1 to 5% by weight, based on the amount of all monomers used.
- The weight ratio of the nonpolymerizable, interface-active compounds (T) used to the monomers (a) is generally 4:1 to 1:4, preferably 2:1 to 1:2, more preferably 1.5:1 to 1:1.5 and, for example, approx. 1:1.
- For the polymerization, the components required are first mixed with one another. The sequence with which the components are mixed for polymerization is unimportant; what is important is merely that, in the preferred polymerization method, the nonpolymerizable, interface-active compound (T) is added to the aqueous polymerization medium before the initiation of the polymerization.
- The mixture is subsequently polymerized thermally and/or photochemically, preferably at −5° C. to 80° C. If polymerization is effected thermally, preference is given to using polymerization initiators which can initiate the polymerization even at comparatively low temperature, for example redox initiators. The thermal polymerization can be undertaken even at room temperature or by heating the mixture, preferably to temperatures of not more than 50° C. The photochemical polymerization is typically undertaken at temperatures of −5 to 10° C. It is also possible to combine photochemical and thermal polymerization with one another, by adding both initiators for the thermal and photochemical polymerization to the mixture. In this case, the polymerization is first initiated photochemically at low temperatures, preferably −5 to +10° C. The heat of reaction released heats the mixture, which additionally initiates the thermal polymerization. By means of this combination, it is possible to achieve a conversion of more than 99%.
- In a further preferred embodiment of the polymerization, it is also possible to perform the reaction with a mixture of a redox initiator system and a thermal initiator which does not decompose until relatively high temperatures. This may, for example, be a water-soluble azo initiator which decomposes within the temperature range from 40° C. to 70° C. The polymerization here is at first initiated at low temperatures of, for example, 0 to 10° C. by the redox initiator system. The heat of reaction released heats the mixture, and this additionally initiates the polymerization by virtue of the initiator which does not decompose until relatively high temperatures.
- The gel polymerization is generally effected without stirring. It can be effected batchwise by irradiating and/or heating the mixture in a suitable vessel at a layer thickness of 2 to 20 cm. The polymerization gives rise to a solid gel. The polymerization can also be effected continuously. For this purpose, for example, a polymerization apparatus possessing a conveyor belt to accommodate the mixture to be polymerized is used. The conveyor belt is equipped with devices for heating and/or for irradiating with UV radiation. In this method, the mixture is poured onto one end of the belt by means of a suitable apparatus, the mixture is polymerized in the course of transport in belt direction, and the solid gel can be removed at the other end of the belt.
- The gel obtained is preferably comminuted and dried after the polymerization. The drying should preferably be effected at temperatures below 100° C. To prevent conglutination, it is possible to use a suitable separating agent for this step. This gives the hydrophobically associating copolymer as granules or powder.
- Further details of the performance of a gel polymerization are disclosed, for example in DE 10 2004 032 304 A1, paragraphs [0037] to [0041].
- Since the polymer powder or granules obtained are generally used in the form of an aqueous solution in the course of application at the site of use, the polymer has to be dissolved in water on site. This may result in undesired lumps with the high molecular weight polymers described. In order to avoid this, it is possible to add an assistant which accelerates or improves the dissolution of the dried polymer in water to the inventive polymers as early as in the course of synthesis. This assistant may, for example, be urea.
- The resulting copolymers preferably have a weight-average molecular weight Mw of 1*106 g/mol to 30*106 g/mol, preferably 5*106 g/mol to 20*106 g/mol.
- To execute the process, an aqueous formulation which comprises, in addition to water, at least the hydrophobically associating copolymer described is used. It is of course also possible to use mixtures of different hydrophobically associating copolymers.
- As well as water, the formulation may also comprise water-miscible organic solvents, in which case the amount of the water should generally comprise at least 75% by weight, preferably at least 90% by weight and more preferably at least 95% by weight based on the sum of all solvents used. Very particular preference is given to using exclusively water as the solvent. The formulation can be made up in freshwater or else in water comprising salts. The formulation can preferably be prepared by initially charging the water, sprinkling in the copolymer as a powder and mixing it with the water, and is preferably made up at ambient temperature.
- According to the invention, the concentration of the polymer in the formulation is 0.1 to 3% by weight based on the sum of all components of the aqueous formulation. The amount is preferably 0.5 to 3% by weight and more preferably 1 to 3% by weight.
- The concentration of the copolymer and hence the viscosity of the formulation used can be determined by the person skilled in the art according to the conditions in the formation.
- The formulation may optionally comprise further components, for example crosslinkers, biocides, stabilizers or salts.
- Further components may especially be water-soluble crosslinkers which can bring about crosslinking of the hydrophobically associating copolymer under deposit conditions.
- Crosslinkers may, for example, be water-soluble compounds comprising di-, tri- or tetravalent metal ions, for example compounds comprising Al(III), Cr(III) or Zr(IV) ions, for example chromium(III) acetate, aluminum(III) citrate, zirconium(IV) salts such as zirconium(IV) lactate or zirconium(IV) acetate. The crosslinkers may also be boric acid or salts thereof.
- The crosslinkers may also be organic crosslinkers, for example aldehydes such as formaldehyde, glyoxal or glutaraldehyde, or organic compounds comprising at least two amino or ammonium groups, for example polyethyleneimines, polyvinylamine or polyetheramines. The crosslinkers may also be microencapsulated crosslinkers in which the crosslinker is released only after the injection of the formulation into the formation.
- The amounts of crosslinker are selected by the person skilled in the art according to the desired properties, for example the desired degree of crosslinking. The amount of crosslinker may, for example, be 1 to 10% by weight based on the amount of the polymer used.
- The performance of process step (1) involves injecting the above-described aqueous formulation which comprises at least the hydrophobically associating copolymer described into the formation through at least one well.
- Process step (1) can be executed as the first process step, and then process step (2) of the process according to the invention. Process step (1) can, however, also be executed only after a first performance of process step (2), especially after water flooding of the formation. This variant is advisable when water production has already risen significantly as a result of sustained water flooding.
- The injection of the aqueous formulation can be undertaken by means of customary apparatus.
- The formulation can be injected by means of customary pumps. The wells are typically lined with cemented steel pipes, and the steel pipes are perforated at the desired site. The formulation enters the mineral oil formation through the perforation in the well. In a manner known in principle, the pressure applied by means of the pumps fixes the flow rate of the formulation and hence also the shear stress with which the aqueous formulation enters the deposit. The process may of course also be performed when the well has not been lined. According to the type of underground formation and the regions to be blocked, a person skilled in the art selects suitable copolymers. The formation of a gel in the underground formation can, according to the copolymer, proceed with use of crosslinkers or else without the use of crosslinkers.
- The copolymers used in accordance with the invention as a constituent of the aqueous formulation, especially those which comprise monomers (a), (b1) and (b2a), are notable for thermal thickening characteristics within particular temperature ranges, which means that the aqueous formulations are notable in that the viscosity thereof at room temperature is lower than at higher temperatures. In general, the viscosity passes through a maximum in the range from approx. 50 to 80° C. The details on this subject are given in the experimental section. Preferred copolymers for this application comprise, as well as the monomers (a) and (b1), monomers (b2a) having sulfo groups. These may more preferably be copolymers comprising monomers (a), acrylamide and 2-acrylamido-2-methylpropanesulfonic acid.
- In a first preferred embodiment of the invention, permeable regions of the formation can therefore be blocked by exploiting the thermal thickening characteristics of the copolymers used. For this embodiment, no crosslinker need be added to the formulation.
- In this first preferred embodiment, the temperature of the aqueous formulation before the injection should preferably be lower than the deposit temperature. “Before the injection” relates to the temperature of the formulation at the surface of the earth before it is injected into the well. The temperature of the aqueous formulation before the injection into the deposit is preferably less than 35° C., more preferably less than 30° C. and, for example, approx. 15° C. to 25° C.
- In this preferred embodiment, the temperature of the aqueous formulation of the hydrophobically associating copolymer is lower than the deposit temperature. After entry into the mineral oil formation, the aqueous formulation naturally flows into the permeable regions of the formation with low flow resistance. Under the influence of the deposit temperature, the aqueous formulation heats up to an increasing degree and accordingly gradually increases in viscosity until ultimate formation of a gel which has such a high viscosity that the permeable regions of the formation are blocked. This variant is suitable especially for formations with a deposit temperature of more than 40° C., preferably more than 45° C., especially 40° C. to 100° C., preferably 45° C. to 90° C., more preferably 50° C. to 75° C. In this embodiment, the temperature of the aqueous formulation before injection into the deposit should be at least 10° C., preferably at least 20° C., lower than the deposit temperature.
- The hydrophobically associating copolymers used in accordance with the invention, especially the already mentioned copolymers comprising monomers (a), (b1) and (b2a) also have shear-diluting characteristics, i.e. the viscosity thereof decreases with increasing shear. It is therefore advisable to inject the aqueous formulations with high flow rate. This retards the heating of the formulation, but the shear-diluting characteristics do not result in mechanical degradation of the copolymer on entry into the formation, and so it regains viscosity after the shear has declined.
- In a second preferred embodiment of the invention, the shear rate on entry of the aqueous copolymer formulation into the formation is therefore at least 30 000 s−1, preferably at least 60 000 s−1 and more preferably at least 90 000 s−1. The shear stress on entry into the formation can be calculated by the person skilled in the art in a manner known in principle on the basis of the Hagen-Poiseuille law using the area flowed through on entry into the formation, the mean pore radius and the volume flow rate. The average porosity of the formation can be calculated in a manner known in principle by measurements on drill cores. The greater the volume flow rate of aqueous formulation injected into the formation, the greater the shear stress will naturally be.
- Copolymers particularly preferred for execution of the outlined
embodiments 1 and 2 of the process comprise monomers (a) of the general formula H2C═CH—O—(CH2)n′—O—(—CH2—CH2—O—)k—(—CH2—CH(R4)—O—)l—H (Ia) where n′ is 2 to 6, preferably 2 to 4 and more preferably 4. R4 in the preferred variant is a hydrocarbyl radical having 3 to 10 carbon atoms, especially an n-propyl radical. In addition, in formula (Ia), k is a number from 20 to 30 and I is a number from 6 to 20, preferably 8 to 18. The amount of the monomers (a) of the formula (Ia) is 0.2 to 5% by weight, preferably 0.5 to 2% by weight. As monomer (b1) the copolymer preferred forembodiments 1 and 2 comprises 40 to 60% by weight of acrylamide, and as monomer (b2a) 35 to 55% by weight of a monomer (b2a) having sulfo groups, preferably 2-acrylamido-2-methylpropane-sulfonic acid or salts thereof. Particular preference is given to using exclusively monomers (b2a) having sulfo groups. - In a third preferred embodiment of the invention, a formulation which additionally comprises one or more crosslinkers which can bring about the crosslinking of the polymer under deposit conditions is used. The crosslinking reaction thus occurs only in the course of heating of the formulation to deposit temperature. For this purpose, the above-described crosslinkers can be used in the aqueous formulation. The crosslinking of the polymer improves the strength of the gel for blockage of the formation. For the third embodiment too, the copolymers particularly suitable for
embodiments 1 and 2 can be used with preference. - For the third embodiment, it is particularly advantageously possible to use copolymers having COOH groups, or those which form COOH groups under formation conditions.
- Copolymers which are particularly advantageous for this third embodiment are therefore those which comprise monomers (a), (b1) and (b2b). Preference is given especially to copolymers comprising monomers (a) of the general formula H2C═CH—O—(CH2)n′—O—(—CH2—CH2—O—)k—(—CH2—CH(R4)l—H (Ia). Preferred ranges for n′, k, l and R4 have already been specified above. (b1) is preferably acrylamide, and (b2b) especially comprises readily hydrolyzable esters with secondary or tertiary ester groups, especially t-butyl (meth)acrylate. Preferred amounts are 0.2 to 5% by weight of monomers (Ia), 70 to 99.7% by weight of (b1) and 0.1 to 10% by weight, preferably 0.2 to 5% by weight, of (b2b).
- The mode of action of the crosslinkers is known in principle to those skilled in the art. In this regard, we make reference to the literature cited at the outset, for example from the review article Boiling et al. “Pushing out the oil with Conformance Control” in Oilfield Review (1994), pages 44 ff. What is essential is that crosslinking reactions do not proceed at a significant rate at room temperature, but only at higher temperatures, especially at temperatures of >50° C. At higher temperatures, —CONR'2 and/or —COOR16 groups present in the polymer can be hydrolyzed to —COOH groups, and the —COOH groups of different copolymer chains can crosslink with one another via complexation with metal ions present in the formulation. It is likewise possible for COOH groups to react with polyethyleneimines and/or forms salts, and thus crosslink the copolymers. The crosslinking forms a high-viscosity gel which blocks the formation.
- In a fourth preferred embodiment of the invention, copolymers which also comprise cationic monomers (b3) as well as monomers (b1) and (b2a) are used in the aqueous formulation. Preferred copolymers for this fourth embodiment comprise 0.2 to 5% by weight, preferably 0.5 to 2% by weight, of monomers (a) of the general formula (Ia), and, as monomers (b1), 30 to 40% by weight of acrylamide. They additionally comprise 25 to 35% by weight of at least one monomer (b2a) having sulfo groups, preferably 2-acrylamido-2-methylpropanesulfonic acid or salts thereof, and 25 to 35% by weight of at least one cationic monomer having ammonium ions, preferably salts of dialkyldiallylammonium, 3-trimethylammoniopropyl(meth)acrylamides and 2-trimethylammonioethyl (meth)acrylates.
- This embodiment can be used, for example, in silicatic formations, especially sandstone formations. However, it can of course also be used in other formations, for example carbonatic formations. Silicatic formations have anionic sites on the surface, which can interact well with the cationic sites of the copolymers used. It is thus possible to form a polymer film on the surface of the rock formation, which constricts free cross sections. Further polymer can be absorbed on the polymer-modified surface. It will be appreciated that this embodiment can also be combined with crosslinking of the copolymer. For this purpose, the crosslinkers already outlined can be used.
- In a fifth preferred embodiment of the invention, the injection of the copolymer used in accordance with the invention is preceded by injection of an aqueous formulation of a polymer having cationic groups. Examples of suitable cationic polymers comprise poly(diallyldimethyl-ammonium chloride), poly(N-acrylamidopropyl-N,N,N-trimethylammonium chloride) or poly(N-methacrylatopropyl-N,N-dimethyl-N-benzylammonium chloride), or corresponding copolymers, for example with acrylamide as a comonomer.
- After the injection of the cationic polymer, the aqueous formulation of the copolymer used in accordance with the invention is injected into the formation, and the surface is cationically modified as a result. The copolymer which has anionic groups and is used in accordance with the invention can be adsorbed efficiently on the cationically modified surface. In a preferred embodiment of the invention, the injection of aqueous formulations of a cationic polymer and of the copolymer used in accordance with the invention can be repeated once or more than once. In this way, a multilayer polymer film of ever greater thickness forms on the formation surface.
- The aqueous copolymer formulation can be injected either through one or more injection wells and/or one or more production wells. This is guided by the specific conditions in the formation.
- Injection into a production well is particularly advisable, for example, when a water-bearing stratum is arranged below a mineral oil-bearing stratum, and water is increasingly being produced from the water-bearing stratum. For injection into production wells, the injection of aqueous flooding media into the injection wells is generally stopped. Measures known in principle to those skilled in the art can ensure that the aqueous copolymer formulation is actually injected into the water-bearing zone and not into the oil-bearing zone. For example, through suitable lining of the well, steel pipes perforated exactly in the region of the water-bearing stratum can inject the copolymer formulation into the water-bearing stratum in a controlled manner. In addition, the penetration of polymer formulation into the oil-bearing stratum can be prevented by simultaneously injecting an inert protection fluid into the oil-bearing stratum.
- In the case of injection into one or more injection wells, the aqueous copolymer formulation naturally flows into the permeable regions of the formation with low flow resistance, and hence exactly through the regions which are to be blocked.
- In process step (2), mineral oil is actually produced by injection of an aqueous flooding medium into the at least one injection well and withdrawing mineral oil through the at least one production well. The aqueous flooding medium injected maintains the pressure and forces the mineral oil from the injection wells in the direction of the production wells.
- The aqueous flooding medium may preferably be water or salt-containing water. In this case, the process is called “water flooding”. It is possible to inject either freshwater or saltwater. For example, seawater can be used for injection, for example in the case of production platforms, or it is possible to use produced formation water, which is reused in this manner. It may be cold water or hot water. The aqueous flooding media may, however, also be steam (“steam flooding”), aqueous formulations comprising surfactants (“surfactant flooding”) or formulations comprising thickening polymers (“polymer flooding”).
- When process step (2) is executed repeatedly, the aqueous flooding media used in each case may be identical aqueous flooding media or have different compositions.
- When step (1) is executed by injection into the injection wells, it is advisable to commence the process with the performance of step (1). This is followed by process step (2). If process step (2) has formed new preferential flow paths, these can be blocked by repetition of step (1), followed by continuation with step (2). It will be appreciated that it is also possible to repeat the sequence of steps (1) and (2) several times.
- The blocking of permeable regions from the production well can advantageously be performed when water production has risen, i.e. after a first performance of process step (2). After the performance of process step (1), mineral oil production is repeated with the new performance of process step (2).
- The examples which follow are intended to illustrate the invention in detail:
- Hydroxybutyl Vinyl Ether Alkoxylate with 22 EO Units and 12 PeO Units
-
H2C═CH—O—(CH2)4—O—(—CH2—CH2—O—)22—(—CH2—CH(C3H7)—O—)12—H - A 1 l stirred stainless steel autoclave is initially charged with 44.1 g of hydroxybutyl vinyl ether. Subsequently, 3.12 g of KOMe (32% in MeOH) are metered in and the methanol is drawn off at 80° C. and approx. 30 mbar. This is followed by heating to 140° C., purging of the reactor with nitrogen and establishment of a nitrogen pressure of 1.0 bar. Then 368 g of EO are metered in within approx. 3 h. After continued reaction at 140° C. for a half hour, the reactor is cooled to 125° C., and a total of 392 g of pentene oxide are metered in over the course of 3.5 h. The reaction continues overnight.
- The product has an OH number of 31.9 mg KOH/g (theory: 26.5 mg KOH/g). The OH number is determined by means of the ESA method.
- Preparation of a Copolymer from 2% by Weight of Monomer M1, 50% by Weight of Acrylamide and 48% by Weight of 2-Acrylamido-2-Methylpropanesulfonic Acid (by Means of Gel Polymerization)
- A plastic bucket with magnetic stirrer, pH meter and thermometer is initially charged with 121.2 g of a 50% aqueous solution of NaATBS (2-acrylamido-2-methylpropanesulfonic acid, sodium salt), and then 155 g of distilled water, 0.6 g of a defoamer (Surfynol® DF-58), 0.2 g of a silicone defoamer (Baysilon® EN), 2.3 g of monomer M1, 114.4 g of a 50% aqueous solution of acrylamide, 1.2 g of pentasodium diethylenetriaminepentaacetate (complexing agent, as a 5% aqueous solution) and 2.4 g of a nonionic surfactant (nonylphenol, alkoxylated with 10 units of ethylene oxide) are added successively.
- After adjusting the pH with a 20% or 2% sulfuric acid solution to a value of 6 and adding the rest of the water, the monomer solution is adjusted to the start temperature of 5° C. The total amount of water is such that—after the polymerization—a solids concentration of approx. 30 to 36% by weight is attained. The solution is transferred to a thermos flask, a temperature sensor for the temperature recording is provided and the solution is purged with nitrogen for 30 minutes. The polymerization is then initiated by adding 1.6 ml of a 10% aqueous solution of a water-soluble cationic azo initiator 2,2′-azobis(2-amidinopropane) dihydrochloride (Wako V-50), 0.12 ml of a 1% aqueous solution of tert-butyl hydroperoxide and 0.24 ml of a 1% sodium sulfite solution. After the initiators have been added, the temperature rises to approx. 80° C. within 15 to 30 min. After 30 min, the reaction vessel is placed into a drying cabinet at approx. 80° C. for approx. 2 h to complete the polymerization. The total duration of the polymerization is approx. 2 h to 2.5 h. A gel block is obtained, which, after the polymerization has ended, is comminuted with the aid of a meat grinder. The gel granules obtained are dried in a fluidized bed dryer at 55° C. for two hours. This gives white, hard granules which are converted to a pulverulent state by means of a centrifugal mill. This gives a copolymer with a weight-average molecular weight of approx. 1*106 g/mol to 30*106 g/mol.
- This is a commercially available copolymer for polymer flooding, formed from approx. 50% by weight of acrylamide and approx. 50% by weight of 2-acrylamido-2-methylpropanesulfonic acid with a weight-average molecular weight Mw of approx. 8 to 13*106 g/mol. In contrast to the copolymers used in accordance with the invention, it does not comprise any hydrophobically associating monomers.
- Preparation of a Copolymer from 2% by Weight of
Monomer 1, 93% by Weight of Acrylamide and 5% by Weight of T-Butyl Acrylate - A 2 l three-neck flask with stirrer and thermometer was initially charged with 337.5 g of water. 0.06 g of sodium hypophosphite, 0.5 g of ammonium persulfate and 7.46 g of butyl acrylate were added successively to the reaction flask. Then it was purged with nitrogen for 45 min. In parallel to this, a monomer solution consisting of 91.2 g of water, 272.56 g of 50 percent aqueous acrylamide solution, 1.03 g of 50 percent aqueous Trilon C solution, 2.93 g of monomer M1, 1.03 g of sodium dodecylsulfate, 0.1 g of sodium hypophosphite and 0.5 g of potassium bromate was prepared.
- 24.0 g of a 7 percent aqueous sodium sulfite solution were likewise prepared as an initiator solution. After the inertization, the monomer solution and the initiator solution were metered in in parallel with a peristaltic pump. The metering time of the monomer solution was 2 h, and that of the initiator solution 2.5 h. In the course of this, it was ensured that the internal temperature did not exceed 50° C. After the metered addition had ended, the mixture was heated to 60° C. Subsequently, 0.375 g of VA044 was added as a further initiator for residual monomer reduction, and the mixture was stirred at 60° C. for 1 h. Finally, 0.75 g of Acticide MBS was dissolved in 13.5 g of water and added. Then the mixture was cooled and transferred.
- Preparation of a Copolymer from 4% by Weight of
Monomer 1, 91% by Weight of Acrylamide and 5% by Weight of T-Butyl Acrylate - Polymer 3 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
-
50 percent aqueous acrylamide solution 266.71 g Butyl acrylate 7.46 g Monomer 1 5.85 g - Preparation of a Copolymer from 1% by Weight of
Monomer 1, 94% by Weight of Acrylamide and 5% by Weight of T-Butyl Acrylate - Polymer 4 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
-
50 percent aqueous acrylamide solution 275.51 g Butyl acrylate 7.46 g Monomer 1 1.46 g - Preparation of a Copolymer from 0.5% by Weight of
Monomer 1, 94.5% by Weight of Acrylamide and 5% by Weight of T-Butyl Acrylate - Polymer 5 was prepared like polymer 2, except that the amounts of the monomers were altered as follows:
-
-
50 percent aqueous acrylamide solution 276.99 g Butyl acrylate 7.46 g Monomer 1 0.73 g - Preparation of a Copolymer from 0.5% by Weight of
Monomer 1, 95.5% by Weight of Acrylamide and 4% by Weight of Sodium Acrylate (by Means of Suspension Polymerization) - A 2 l jacketed reactor with stirrer and water separator is initially charged with 600 g of Exxsol D40, 4 g of a 25 percent solution of a polymeric stabilizer for water-in-oil suspensions are added and the mixture is heated to 35° C. In the course of which, inertization is effected by purging with nitrogen for 90 min. In a beaker, 310.40 g of a 50 percent aqueous acrylamide solution, 18.05 g of a 35 percent sodium acrylate solution, 0.6 g of a 50 percent aqueous Trilon C, 0.81 g of
monomer 1 and 10.12 g of water are mixed. 10 percent sulfuric acid is used to adjust the pH to 6.0. Then 1.62 of a 10 percent aqueous solution of V50 (Wako) and 11.52 g of a 1 percent sodium sulfite solution are added to the monomer solution. The monomer solution is introduced into the inertized oil phase and stirred at 350 rpm for 4 min. Thereafter, 3.6 g of a 1 percent aqueous solution of tert-butyl hydroperoxide are added. The polymerization commences rapidly and reaches 85° C. after a few minutes. After 15 min, the mixture is heated to boiling and the water is distilled off by azeotropic means. After the complete removal of the water, the mixture is cooled to room temperature and filtered. - Preparation of a Copolymer from 1% by Weight of
Monomer 1, 95% by Weight of Acrylamide and 4% by Weight of Sodium Acrylate -
Polymer 7 was prepared like polymer 6, except that the amounts of the monomers were altered as follows: -
50 percent aqueous acrylamide solution 308.70 g 35 percent aqueous sodium acrylate solution 18.05 g Monomer 1 1.62 g - Preparation of a Copolymer from 2% by Weight of
Monomer 1, 94% by Weight of Acrylamide and 4% by Weight of Sodium Acrylate - Polymer 8 was prepared like polymer 6, except that the amounts of the monomers were altered as follows:
-
50 percent aqueous acrylamide solution 305.50 g 35 percent aqueous sodium acrylate solution 18.05 g Monomer 1 3.24 g - Preparation of a Copolymer from 4% by Weight of
Monomer 1, 92% by Weight of Acrylamide and 4% by Weight of Sodium Acrylate - Polymer 9 was prepared like polymer 26, except that the amounts of the monomers were altered as follows:
-
50 percent aqueous acrylamide solution 299.06 g 35 percent aqueous sodium acrylate solution 18.05 g Monomer 1 6.48 g - Preparation of a Copolymer from 0.5% by Weight of Acrylic Acid, 39.5% by Weight of Acrylamide and 60% by Weight of 2-Acrylamido-2-Methylpropanesulfonic Acid
- Polymer C2 was prepared like polymer 6 (suspension polymerization), except that the abovementioned monomers were used in the amounts specified.
- Preparation of a Copolymer from 3.1% by Weight of Sodium Acrylate, 96.4% by Weight of Acrylamide and 0.5% by Weight of
Monomer 1 - The procedure was as in example 1 (gel polymerization), except that the above-mentioned monomers were used in the amounts specified.
- Preparation of a Copolymer from 3.1% by Weight of Sodium Acrylate, 95.9% by Weight of Acrylamide and 1.0% by Weight of
Monomer 1 - The procedure was as in example 1 (gel polymerization), except that the above-mentioned monomers were used in the amounts specified.
- Preparation of a copolymer from 3.1% by weight of sodium acrylate, 94.9% by weight of Acrylamide and 2.0% by Weight of
Monomer 1 - The procedure was as in example 1 (gel polymerization), except that the above-mentioned monomers were used in the amounts specified.
- Preparation of a Copolymer from 3.1% by Weight of Sodium Acrylate, 92.8% by Weight of Acrylamide and 4.1% by Weight of
Monomer 1 - The procedure was as in example 1 (gel polymerization), except that the above-mentioned monomers were used in the amounts specified.
- Preparation of a Copolymer from 3.1% by Weight of Sodium Acrylate, 96.9% by Weight of Acrylamide
- The procedure was as in example 1 (gel polymerization), except that the above-mentioned monomers were used in the amounts specified. No
monomer 1 was used. - In the test series which follow, the thermal thickening action of the polymers used is tested.
- Solutions of
polymers 1 and Cl were made up in a concentration of in each case 1200 ppm in tap water, and the viscosity of each of the solutions was measured at 30° C., 60° C., 90° C. and 120° C.FIG. 1 shows the result of the viscosity measurements. - It is clearly evident that the viscosity of the polymer used in accordance with the invention rises with rising temperature up to a viscosity maximum at 60° C. and then decreases again, while the comparative polymer has a falling viscosity with rising temperature. The polymer used in accordance with the invention can thus be injected into the mineral oil formation low temperatures, and follows the preferred flow paths. The viscosity increases in the course of heating under the sole influence of the deposit temperature and thus leads to the formation of a highly viscous gel in the flow paths.
- A 2% solution of
inventive polymer 1 in tap water was prepared. This solution was highly viscous but still free-flowing at room temperature, especially at high shear rates as occur in the course of pumping of the polymer solution. In the course of heating to 60° C. at a low shear rate, the viscosity of the polymer solution rose significantly and it was barely free-flowing any longer. - The Brookfield viscosity (in mPas) of solutions of 0.5% by weight of polymers 10 to 13 and C2 and C3 in fresh water and in a salt solution was measured at various temperatures.
- The salt solution had the following composition:
-
Salt Amount [g/l] NaCl 23.5 Na2SO4*10 H2O 8.9 KCl 0.7 MgCl2*6 H2O 10.6 CaCl2*2 H2O 2.2 NaHCO3 0.2 Total 46.1 - The results are compiled in tables 1 and 2:
-
TABLE 1 Results of the viscosity measurements in fresh water Viscosity η [m Pas] Polymer Polymer Polymer Polymer T 10 11 12 13 C2 C3 [° C.] 0.5 % M1 1% M1 2% M1 4.1% M1 — — 20 78 150 252 280 500 45 40 75 345 700 800 350 65 60 40 550 1860 1700 250 90 80 2750 -
TABLE 2 Results of the viscosity measurements in salt water Viscosity η [m Pas] Polymer Polymer Polymer Polymer T 10 11 12 13 C2 C3 [° C.] 0.5 % M1 1% M1 2% M1 4.1% M1 — — 20 120 170 390 155 40 85 40 180 470 1700 550 20 45 60 250 1000 2500 1000 15 30 80 3300 - The results show that the polymers which comprise monomer M1 and are to be used in accordance with the invention exhibit excellent thermal thickening characteristics in salt water. Comparative polymers C2 and C3 have only very low viscosities in salt water, and the viscosities decrease in the course of heating. Due to these properties, the polymers are outstandingly suitable for blocking of underground formations. The polymers can be injected efficiently at low viscosities and the viscosity increases very significantly underground.
- The Brookfield viscosity of each of the polymers used was measured in aqueous solution at room temperature. The results are compiled in tables 3 and 4 below.
-
TABLE 3 Viscosities of polymers 3 to 5 Composition acrylamide/tert-butyl Brookfield viscosity [mPas] acrylate/monomer M1 at RT Polymer No. [in % by wt.] (aqueous solution, 20% by wt.) 2 93/5/2 208 3 91/5/4 440 4 94/5/1 260 5 945/5/0.5 260 -
TABLE 4 Viscosities of polymers 6 to 9 Composition Brookfield Viscosity [mPas] acrylamide/sodium in water at RT acrylate/monomer M1 0.5% by weight 1% by weight Polymer No. [in % by wt.] of polymer of polymer 6 95.5/4/0.5 8 28 7 95/4/1 90 150 8 94/4/2 90 190 9 92/4/4 210 320 - In order to be able to test the properties of the polymers used with regard to gel formation properties under formation conditions, gel formulation was studied in seawater at 80° C. The combination of 80° C. and salt-containing water simulates the conditions in a typical mineral oil deposit.
- The t-butyl ester units of copolymers 2 to 5 are hydrolyzed to an extent of approx. 50% at 80° C. in seawater within 2 h, and form COOH groups.
- A synthetic seawater of the following composition was used:
- 500 g of deionized water
- In addition, crosslinkers were added in some experiments. The crosslinkers used were:
- Crosslinker 1: 50% by weight aqueous chromium(III) acetate solution
- Crosslinker 2: 33% by weight of aqueous polyethyleneimine solution, Mw approx. 75 000 g/mol, pH 11.4 (Lupasol® PS)
- Crosslinker 3: 40% by weight of aqueous polyethyleneimine solution, Mw approx. 25 000 g/mol, pH 11.0 (Basomin® G 500)
- The gel formation tests were conducted as follows.
-
- 100 ml of a 5% solution of the polymers in seawater (or in fresh water for comparative purposes) are initially charged in a screwtop bottle. If crosslinkers are used, the crosslinker is added by means of a plastic syringe and the screwtop bottle is closed. The bottle is shaken until the mixture is homogeneous and then placed in the drying cabinet at 80° C.
- The sample is assessed visually at 5 minute intervals, by placing the bottle on its lid and assessing the flow characteristics of the contents and assigning a gel code. The time when gel code B is attained is noted. The appearance of the gels and the assignment of the gel codes is detailed below.
- A—no detectable gel formed. The gel appears to have the same viscosity (fluidity) as the original polymer solution, and no gel can be discovered visually.
- B—highly mobile gel. The gel appears to be only a bit tackier than the original polymer solution of relatively low viscosity.
- C—flowing gel. The majority of the obviously detectable gel flows into the bottle lid and back.
- D—moderately flowing gel. A small amount (−5-15%) of the gel flows into the bottle lid and back, usually characterized as a ‘tonguing’ gel (i.e. once the gel hangs out of the bottle, it can flow back into the bottle when the bottle is slowly turned upright).
- E—barely flowing gel. The gel flows slowly into the bottle lid and/or a significant portion (>15%) of the gel does not flow into the bottle lid and back.
- F—highly deformable gel. The gel does not flow into the bottle lid and back (gel barely flows to reach the bottle lid).
- G—moderately deformable non-flowing gel. Half of the gel flows to the bottle lid and back.
- H—an only slightly deformable, non-flowing gel. The gel surface deforms slightly and the deformation is reversed again.
- I—rigid gel. There is no longer any gel surface deformation.
- J—the ringing of rigid gel. After knocking on the bottle, the gel rings like a tuning fork and mechanical vibration can be perceived.
- The results and test conditions for polymers 2 to 5 are shown in table 5 below, and the results for polymers 6 to 9 in table 6 below.
-
TABLE 5 Gel formation tests at 80° C., test conditions and results Amount of Polymer polymer Gel code B Gel code J No. [% by wt.] Medium Crosslinker after [min] after [min] 2 5 Fresh water Crosslinker1/250 ppm 45 55 3 5 Fresh water Crosslinker1/250 ppm 60 70 4 5 Fresh water Crosslinker1/250 ppm 55 65 5 5 Fresh water Crosslinker1/250 ppm 55 70 2 5 Seawater Crosslinker 1/250 ppm 50 60 3 5 Seawater Crosslinker 1/250 ppm 65 70 4 5 Seawater Crosslinker 1/250 ppm 55 70 5 5 Seawater Crosslinker 1/250 ppm 50 75 2 5 Fresh water Crosslinker 2/2000 ppm 3 h 10 min 3 h 30 min 3 5 Fresh water Crosslinker 2/2000 ppm 3 h 30 min 3 h 45 min 4 5 Fresh water Crosslinker 2/2000 ppm 3 h 20 min 3 h 35 min 5 5 Fresh water Crosslinker 2/2000 ppm 2 h 55 min 3 h 05 min 2 5 Fresh water Crosslinker 3/2000 ppm 10 h 50 min 13 h 10 min 3 5 Fresh water Crosslinker 3/2000 ppm 12 h 15 min 14 h 45 min 4 5 Fresh water Crosslinker 3/2000 ppm 11 h 35 min 12 h 55 min 5 5 Fresh water Crosslinker 3/2000 ppm 10 h 25 min 11 h 15 min 2 5 Seawater Crosslinker 2/2000 ppm 14 h 36 h 3 5 Seawater Crosslinker 2/2000 ppm 13 h 38 h 4 5 Seawater Crosslinker 2/2000 ppm 12.5 h 35 h 5 5 Seawater Crosslinker 2/2000 ppm 9.5 h 33 h 2 5 Seawater Crosslinker 3/2000 ppm 12 h 33 h 2 5 Seawater Crosslinker 3/2000 ppm 14 h 35 h 3 5 Seawater Crosslinker 3/2000 ppm 12 h 30 h 5 5 Seawater Crosslinker 3/2000 ppm 7 h 28 h -
TABLE 6 Gel formation tests at 80° C., test conditions and results; the crosslinker was used in each case in an amount of 250 ppm. Time until Amount of attainment Final strength Polymer polymer of gel code Attained Gel code No. [% by wt.] Medium B [min] after [min] attained 6 3 Seawater 15 30 J 7 3 Seawater 15 30 J 8 2 Seawater 15 30 I 9 2 Seawater 15 30 I
Claims (22)
H2C═C(R1)—R2—O—(—CH2—CH(R3)—O—)k—(—CH2—CH(R4)—O—)l—R5 (I),
H2C═C(R1)—O—(—CH2—CH(R3)—O—)k—R6 (II),
H2C═C(R1)—(C═O)—O—(—CH2—CH(R3)—O—)k—R6 (III),
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US8783356B2 (en) | 2009-05-20 | 2014-07-22 | Basf Se | Hydrophobically associating copolymers |
US9701890B2 (en) | 2012-11-14 | 2017-07-11 | Basf Se | Process for tertiary mineral oil production |
US20190031946A1 (en) * | 2016-01-13 | 2019-01-31 | Basf Se | Method for tertiary petroleum recovery by means of a hydrophobically associating polymer |
US11220624B2 (en) | 2018-07-30 | 2022-01-11 | Championx Usa Inc. | Salt-tolerant, fast-dissolving, water-soluble rheology modifiers |
US11332563B2 (en) | 2018-07-30 | 2022-05-17 | Ecolab Usa Inc. | Fast dissolving, water soluble, hydrophobically-modified polyelectrolytes |
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US9051503B2 (en) * | 2010-11-24 | 2015-06-09 | Basf Se | Use of hydrophobically associated copolymer as an additive in specific oilfield applications |
FR2994977B1 (en) * | 2012-09-03 | 2016-01-22 | Poweltec | USE OF THERMO THICKENING POLYMERS IN THE GAS AND OIL INDUSTRY |
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